Effect of point-of-use disinfection, flocculation and combined flocculation-disinfection on drinking water quality in western Kenya

Effect of microplastics on sodium hypochlorite disinfection and changes in its toxicity on zebrafish

The presence of microplastics (MPs) in water may affect the efficacy of the disinfection process and induce toxicity changes to MPs themselves during disinfection. Therefore, this study evaluated the two-way effects of polyethylene microplastic (MP) particles in water and wastewater during sodium hypochlorite (NaClO) disinfection. On the one hand, it has been confirmed that the presence of MPs reduced the disinfection efficiency of NaClO. The required CT (concentration of the disinfection × contact time) for a 2-4-log inactivation of Escherichia coli (E. coli) in different water samples was in the order of deionized water < turbid water (1 NTU) < water with MPs (1 mg/L) < turbid water (10 NTU). On the other hand, although exposure to MPs did induce significant changes in the activities of superoxide dismutase and glutathione, compared to pristine MPs, the MPs treated by NaClO at current conditions (0.3 and 3.0 mg/L for 30 min) did not show significant changes in their toxicity on zebrafish, at an MP exposure concentration of 1 mg/L. There was no significant difference in the survival rate and weight growth rate, neither as in the activities of the oxidative stress-related enzymes (superoxide dismutase, catalase, glutathione, glutathione peroxidase, and glutathione s-transferase) in both gut and muscle tissues of the zebrafish, between exposure to the pristine and NaClO-treated MPs. It is indicated that NaClO disinfection commonly applied for water and wastewater treatment would not pose a serious concern to effluent safety in the presence of mild levels of MPs.

Wilderness Medical Society Clinical Practice Guidelines on Water Treatment for Wilderness, International Travel, and Austere Situations: 2024 Update

To provide guidance to medical providers, wilderness users, and travelers, the Wilderness Medical Society convened an expert panel to develop evidence-based guidelines for treating water in situations where the potability of available water is not assured, including wilderness and international travel, areas impacted by disaster, and other areas without adequate sanitation. The guidelines present the available methods for reducing or eliminating microbiological contamination of water for individuals, groups, or households; evaluation of their effectiveness; and practical considerations. The evidence base includes both laboratory and clinical publications. The panel graded the recommendations based on the quality of supporting evidence and the balance between benefits and risks/burdens according to the criteria published by the American College of Chest Physicians.

Field and Laboratory Assessment of a New Electrolytic Point-of-Use Water Treatment Technology

This research creates and implements a new electrolytic point-of-use water treatment (POUWT) device. Device development began by applying two voltages common to commercially available batteries to an apparatus with either two silver or copper wires submerged into synthetic groundwater. The effects of wire diameter, ionic strength of groundwater, and other POUWT parameters on metallic ion release were analyzed. We determined that the silver wire apparatus need only to be run for 2 min at 9 V to yield the target 50 µg/L concentration for water treatment. The 50 µg/L silver yielded up to a 5-log reduction in E. coli bacteria. The copper wire apparatus was excluded in prototype fabrication because it required 62 min to release the target 500 µg/L for disinfection when nine volts were applied to the system and was less effective in disinfection than silver wires. The electrolytic prototype was evaluated in 20 households in Limpopo, South Africa, over a four-week period. The device achieved a 2-log reduction in total coliform bacteria in household drinking water, which is comparable to the field performance of other POUWT devices in low-resource settings. The device also consistently released enough silver sufficient for disinfection while remaining below the WHO drinking water guideline.

Interventions promoting uptake of water, sanitation and hygiene (WASH) technologies in low- and middle-income countries: An evidence and gap map of effectiveness studies

Background

Lack of access to and use of water, sanitation and hygiene (WASH) cause 1.6 million deaths every year, of which 1.2 million are due to gastrointestinal illnesses like diarrhoea and acute respiratory infections like pneumonia. Poor WASH access and use also diminish nutrition and educational attainment, and cause danger and stress for vulnerable populations, especially for women and girls. The hardest hit regions are sub-Saharan Africa and South Asia. Sustainable Development Goal (SDG) 6 calls for the end of open defecation, and universal access to safely managed water and sanitation facilities, and basic hand hygiene, by 2030. WASH access and use also underpin progress in other areas such as SDG1 poverty targets, SDG3 health and SDG4 education targets. Meeting the SDG equity agenda to "leave none behind" will require WASH providers prioritise the hardest to reach including those living remotely and people who are disadvantaged.

Objectives

Decision makers need access to high-quality evidence on what works in WASH promotion in different contexts, and for different groups of people, to reach the most disadvantaged populations and thereby achieve universal targets. The WASH evidence map is envisioned as a tool for commissioners and researchers to identify existing studies to fill synthesis gaps, as well as helping to prioritise new studies where there are gaps in knowledge. It also supports policymakers and practitioners to navigate the evidence base, including presenting critically appraised findings from existing systematic reviews.

Methods

This evidence map presents impact evaluations and systematic reviews from the WASH sector, organised according to the types of intervention mechanisms, WASH technologies promoted, and outcomes measured. It is based on a framework of intervention mechanisms (e.g., behaviour change triggering or microloans) and outcomes along the causal pathway, specifically behavioural outcomes (e.g., handwashing and food hygiene practices), ill-health outcomes (e.g., diarrhoeal morbidity and mortality), nutrition and socioeconomic outcomes (e.g., school absenteeism and household income). The map also provides filters to examine the evidence for a particular WASH technology (e.g., latrines), place of use (e.g., home, school or health facility), location (e.g., global region, country, rural and urban) and group (e.g., people living with disability). Systematic searches for published and unpublished literature and trial registries were conducted of studies in low- and middle-income countries (LMICs). Searches were conducted in March 2018, and searches for completed trials were done in May 2020. Coding of information for the map was done by two authors working independently. Impact evaluations were critically appraised according to methods of conduct and reporting. Systematic reviews were critically appraised using a new approach to assess theory-based, mixed-methods evidence synthesis.

Results

There has been an enormous growth in impact evaluations and systematic reviews of WASH interventions since the International Year of Sanitation, 2008. There are now at least 367 completed or ongoing rigorous impact evaluations in LMICs, nearly three-quarters of which have been conducted since 2008, plus 43 systematic reviews. Studies have been done in 83 LMICs, with a high concentration in Bangladesh, India, and Kenya. WASH sector programming has increasingly shifted in focus from what technology to supply (e.g., a handwashing station or child's potty), to the best way in which to do so to promote demand. Research also covers a broader set of intervention mechanisms. For example, there has been increased interest in behaviour change communication using psychosocial "triggering", such as social marketing and community-led total sanitation. These studies report primarily on behavioural outcomes. With the advent of large-scale funding, in particular by the Bill & Melinda Gates Foundation, there has been a substantial increase in the number of studies on sanitation technologies, particularly latrines. Sustaining behaviour is fundamental for sustaining health and other quality of life improvements. However, few studies have been done of intervention mechanisms for, or measuring outcomes on sustained adoption of latrines to stop open defaecation. There has also been some increase in the number of studies looking at outcomes and interventions that disproportionately affect women and girls, who quite literally carry most of the burden of poor water and sanitation access. However, most studies do not report sex disaggregated outcomes, let alone integrate gender analysis into their framework. Other vulnerable populations are even less addressed; no studies eligible for inclusion in the map were done of interventions targeting, or reporting on outcomes for, people living with disabilities. We were only able to find a single controlled evaluation of WASH interventions in a health care facility, in spite of the importance of WASH in health facilities in global policy debates. The quality of impact evaluations has improved, such as the use of controlled designs as standard, attention to addressing reporting biases, and adequate cluster sample size. However, there remain important concerns about quality of reporting. The quality and usefulness of systematic reviews for policy is also improving, which draw clearer distinctions between intervention mechanisms and synthesise the evidence on outcomes along the causal pathway. Adopting mixed-methods approaches also provides information for programmes on barriers and enablers affecting implementation.

Conclusion

Ensuring everyone has access to appropriate water, sanitation, and hygiene facilities is one of the most fundamental of challenges for poverty elimination. Researchers and funders need to consider carefully where there is the need for new primary evidence, and new syntheses of that evidence. This study suggests the following priority areas:Impact evaluations incorporating understudied outcomes, such as sustainability and slippage, of WASH provision in understudied places of use, such as health care facilities, and of interventions targeting, or presenting disaggregated data for, vulnerable populations, particularly over the life-course and for people living with a disability;Improved reporting in impact evaluations, including presentation of participant flow diagrams; andSynthesis studies and updates in areas with sufficient existing and planned impact evaluations, such as for diarrhoea mortality, ARIs, WASH in schools and decentralisation. These studies will preferably be conducted as mixed-methods systematic reviews that are able to answer questions about programme targeting, implementation, effectiveness and cost-effectiveness, and compare alternative intervention mechanisms to achieve and sustain outcomes in particular contexts, preferably using network meta-analysis.

Wilderness Medical Society Clinical Practice Guidelines for Water Disinfection for Wilderness, International Travel, and Austere Situations

To provide guidance to clinicians, the Wilderness Medical Society convened experts to develop evidence-based guidelines for water disinfection in situations where the potability of available water is not ensured, including wilderness and international travel, areas affected by disaster, and other areas without adequate sanitation. The guidelines present the available methods for reducing or eliminating microbiologic contamination of water for individuals, groups, or households; evaluation of their effectiveness; and practical considerations. The evidence evaluation includes both laboratory and clinical publications. The panel graded the recommendations based on the quality of supporting evidence and the balance between benefits and risks or burdens, according to the criteria published by the American College of Chest Physicians.

Advantages of a ClO2/NaClO combination process for controlling the disinfection by-products (DBPs) for high algae-laden water

Chlorine dioxide (ClO₂) has been widely used in the process of preoxidation and disinfection as an excellent water treatment reagent. However, the inorganic by-products produced by ClO₂, such as chlorite (ClO₂^-) and chlorate (ClO₃^-) are harmful to human health, and this has become a potential problem when using ClO₂ in drinking water treatment. In this study, ClO₂ alone and a ClO₂/NaClO combination process were carried out to evaluate the algae removal efficiency of the treatment and the formation of disinfection by-products (DBPs: chlorite, chlorate, trihalomethanes and haloacetic acids) for high algae-laden water with 124.16 µg L^-1 chlorophyll a (Chl.a) content. The results show that disinfection with 1.5 mg L^-1 ClO₂ alone results in a ClO₂^- concentration exceeding 0.7 mg L^-1. ClO₂ preoxidation/ClO₂ disinfection is applicable for the control of effluent quality, but the ClO₂^- concentration still has an excessive risk when using 0.8 mg L^-1 and 0.6 mg L^-1 ClO₂ for the two process, respectively. In the ClO₂/NaClO combination process, the ClO₂^- concentration is below 0.6 mg L^-1, and trihalomethane (THM) and haloacetic acid (HAA) concentrations are lower than 60% of the maximum contaminant levels (MCLs) set by the World Health Organization (WHO). Further, the formation of ClO₂^- is more effectively controlled by NaClO preoxidation/ClO₂ disinfection than ClO₂ preoxidation/NaClO disinfection.

Understanding the Impacts of Short-Term Climate Variability on Drinking Water Source Quality: Observations From Three Distinct Climatic Regions in Tanzania

Climate change is expected to increase waterborne diseases especially in developing countries. However, we lack understanding of how different types of water sources (both improved and unimproved) are affected by climate change, and thus, where to prioritize future investments and improvements to maximize health outcomes. This is due to limited knowledge of the relationships between source water quality and the observed variability in climate conditions. To address this gap, a 20-month observational study was conducted in Tanzania, aiming to understand how water quality changes at various types of sources due to short-term climate variability. Nine rounds of microbiological water quality sampling were conducted for Escherichia coli and total coliforms, at three study sites within different climatic regions. Each round included approximately 233 samples from water sources and 632 samples from households. To identify relationships between water quality and short-term climate variability, Bayesian hierarchical modeling was adopted, allowing these relationships to vary with source types and sampling regions to account for potentially different physical processes. Across water sources, increases in E. coli/total coliform levels were most closely related to increases in recent heavy rainfall. Our key recommendations to future longitudinal studies are (a) demonstrated value of high sampling frequency and temporal coverage (a minimum of 3 years) especially during wet seasons; (b) utility of the Bayesian hierarchical models to pool data from multiple sites while allowing for variations across space and water sources; and (c) importance of a multidisciplinary team approach with consistent commitment and sharing of knowledge.

Laboratory Efficacy and Disinfection by-Product Formation of a Coagulant/Disinfectant Tablet for Point-of-Use Water Treatment

Coagulant/disinfection products (CDPs) are a point-of-use (POU) water treatment technique that can improve microbial quality, reduce turbidity, and produce a free chlorine residual (FCR), serving as a potentially effective option for decentralized water treatment in a variety of contexts, including humanitarian emergencies. A novel CDP with a sodium dichloroisocyanurate-based disinfectant was evaluated with regard to its laboratory water treatment efficacy and generation of disinfection byproducts (DBPs). The CDP water treatment performance was assessed relative to bacteriological (E. coli) humanitarian water quality objectives, World Health Organization recommendations for evaluating POU water treatment options, and available DBP regulations and guidelines. At least 4 log10 E. coli reductions, for a “highly protective” status with regard to bacterial reductions, were attained in the tested conditions. Treated waters were consistently below 10 MPN/100 mL with regard to E. coli concentrations, with the majority of samples showing no detectable E. coli. For most conditions, target FCR values were not attained. Treated water turbidity levels were mostly between 5 NTU and 10 NTU. DBP levels were below the regulatory and health-based targets for both families of DBPs studied. This study has served to identify the performance envelopes of the CDP tested under challenging conditions.

Household Water Treatment and Cholera Control

Water, sanitation, and hygiene are one part of a cholera control strategy. Household water treatment (HWT) in particular has been shown to improve the microbiological quality of stored water and reduce the disease burden. We conducted a systematic review of published and gray literature to determine the outcomes and impacts of HWT in preventing cholera specifically. Fourteen manuscripts with 18 evaluations of HWT interventions in cholera were identified. Overall, a moderate quality of evidence suggests that HWT interventions reduce the burden of disease in cholera outbreaks and the risk of disease transmission. Appropriate training for users and community health worker follow-up are necessary for use. Barriers to uptake include taste and odor concerns, and facilitators include prior exposure, ease of use, and links to preexisting development programming. Further research on local barriers and facilitators, HWT filters, scaling up existing development programs, program sustainability, integrating HWT and oral cholera vaccine, and monitoring in low-access emergencies is recommended.

Adherence to Point-of-Use Water Treatment over Short-Term Implementation: Parallel Crossover Trials of Flocculation-Disinfection Sachets in Pakistan and Zambia

The health benefits of point-of-use (POU) water treatment can only be realized through high adherence: correct, consistent, and sustained use. We conducted parallel randomized, longitudinal crossover trials measuring short-term adherence to two single-use flocculant-disinfectant sachets in Pakistan and Zambia. In both trials, adherence declined sharply for both products over the eight week surveillance periods, with overall lower adherence to both products in Zambia. There was no significant difference in adherence between the two products. Estimated median daily production of treated water dropped over the crossover period from 2.5 to 1.4 L person^-1 day^-1 (46% decline) in Pakistan and from 1.4 to 1.1 L person^-1 day^-1 (21% decline) in Zambia. The percentage of surveillance points with detectable total chlorine in household drinking water declined from 70% to 49% in Pakistan and rose marginally from 28% to 30% in Zambia. The relatively low and decreasing adherence observed in this study suggests that these products would have provided little protection from waterborne disease risk in these settings. Our findings underscore the challenge of achieving high adherence to POU water treatment, even under conditions of short-term adoption with intensive follow-up.

Sodium hypochlorite dosage for household and emergency water treatment: updated recommendations

Household water treatment with chlorine can improve the microbiological quality of household water and reduce diarrheal disease. We conducted laboratory and field studies to inform chlorine dosage recommendations. In the laboratory, reactors of varying turbidity (10-300 NTU) and total organic carbon (0-25 mg/L addition) were created, spiked with Escherichia coli, and dosed with 3.75 mg/L sodium hypochlorite. All reactors had >4 log reduction of E. coli 24 hours after chlorine addition. In the field, we tested 158 sources in 22 countries for chlorine demand. A 1.88 mg/L dosage for water from improved sources of <5 or <10 NTU turbidity met free chlorine residual criteria (≤2.0 mg/L at 1 hour, ≥0.2 mg/L at 24 hours) 91-94% and 82-87% of the time at 8 and 24 hours, respectively. In unimproved water source samples, a 3.75 mg/L dosage met relaxed criteria (≤4.0 mg/L at 1 hour, ≥0.2 mg/L after 24 hours) 83% and 65% of the time after 8 and 24 hours, respectively. We recommend water from improved/low turbidity sources be dosed at 1.88 mg/L and used within 24 hours, and from unimproved/higher turbidity sources be dosed at 3.75 mg/L and consumed within 8 hours. Further research on field effectiveness of chlorination is recommended.

Evaluating four measures of water quality in clay pots and plastic safe storage containers in Kenya

Household water treatment with chlorine can improve microbiological quality and reduce diarrhea. Chlorination is typically assessed using free chlorine residual (FCR), with a lower acceptable limit of 0.2 mg/L, however, accurate measurement of FCR is challenging with turbid water. To compare potential measures of adherence to treatment and water quality, we chlorinated recently-collected water in rural Kenyan households and measured total chlorine residual (TCR), FCR, oxidation reduction potential (ORP), and E. coli concentration over 72 h in clay and plastic containers. Results showed that 1) ORP served as a useful proxy for chlorination in plastic containers up to 24 h; 2) most stored water samples disinfected by chlorination remained significantly less contaminated than source water for up to 72 h, even in the absence of FCR; 3) TCR may be a useful proxy indicator of microbiologic water quality because it confirms previous chlorination and is associated with a lower risk of E. coli contamination compared to untreated source water; and 4) chlorination is more effective in plastic than clay containers presumably because of lower chlorine demand in plastic.

Integrating Water Treatment into Antenatal Care: Impact on Use of Maternal Health Services and Household Water Treatment by Mothers-Rural Uganda, 2013

To increase maternal health service use and household water treatment (HWT), free water treatment kits were provided at first antenatal care (ANC) visits and free water treatment sachet refills were provided at follow-up ANC visits, delivery, and postnatal visits in 46 health facilities in rural Uganda. We evaluated the impact by surveying 226 women in the initiative (intervention group) and 207 women who received ANC before the initiative began (comparison group). There was no differences in the percentages of intervention and comparison group women with ≥ 4 ANC visits; however, a higher percentage of intervention group women reported treating their drinking water (31.7% versus 19.7%, P = 0.01), and had free chlorine residual in stored water (13.5% versus 3.4%, P = 0.02) than comparison group women. The intervention did not appear to motivate increased maternal health service use, but demonstrated improvements in HWT.

A Novel Use for Potassium Alum as Controlling Agent Against Periplaneta americana (Dictyoptera: Blattidae)

In this work, we present our results on the use of potassium alum as an environmentally friendly insecticide. This compound has the potential to rid our homes, schools, hotels, restaurants, and ships of cockroach infestations. This compound is environmentally friendly and has no hazardous effects on plant, animal, or human ecosystems. Alum was approved for medical use a long time ago. In our laboratory, we developed a novel method using potassium alum as an environmentally friendly insecticide to kill the most common cockroach in the subtropical region, Periplaneta americana (L.). Adult and nymph-staged cockroaches were left to feed on potassium alum per individual insect after a period of food deprivation. The mortality was recorded as LT50. The younger nymphs the third and early fourth instars died within 4 d of feeding after consuming an average of 0.3 mg per individual insect. Gravid females were highly susceptible to alum toxicity and experienced a higher mortality rate, with an average of 3 mg per individual female. The oothecae of the normal untreated females were 8.1 mm long and 4.13 mm wide and weighed 94 mg. The eggs laid by the treated gravid females were underweight and exhibited a dwarfism shape, and these eggs did not hatched if the females consumed the potassium alum before laying eggs. The results revealed that the adult male and female cockroaches have to consume 1 mg and 2.7 mg, respectively, of potassium alum to kill 100% of them after 1 month of ingestion. The potassium alum had to be ingested by the cockroaches to affect mortality. The effect of potassium alum was attributed to chronic toxicity and not acute toxicity. The potential applications of this novel technique will be discussed.

Microbiological effectiveness of household water treatment technologies under field use conditions in rural Tanzania

OBJECTIVES

To assess the microbiological effectiveness of several household water treatment and safe storage (HWTS) options in situ in Tanzania, before consideration for national scale-up of HWTS.

METHODS

Participating households received supplies and instructions for practicing six HWTS methods on a rotating 5-week basis. We analysed 1202 paired samples (source and treated) of drinking water from 390 households, across all technologies. Samples were analysed for thermotolerant (TTC) coliforms, an indicator of faecal contamination, to measure effectiveness of treatment in situ.

RESULTS

All HWTS methods improved microbial water quality, with reductions in TTC of 99.3% for boiling, 99.4% for Waterguard^™ brand sodium hypochlorite solution, 99.5% for a ceramic pot filter, 99.5% for Aquatab^® sodium dichloroisocyanurate (NaDCC) tablets, 99.6% for P&G Purifier of Water^™ flocculent/disinfectant sachets, and 99.7% for a ceramic siphon filter. Microbiological performance was relatively high compared with other field studies and differences in microbial reductions between technologies were not statistically significant.

CONCLUSIONS

Given that microbiological performance across technologies was comparable, decisions regarding scale-up should be based on other factors, including uptake in the target population and correct, consistent, and sustained use over time.

Efficacy of aqueous plant extract in disinfecting water of different physicochemical properties

This study explored the possibility of disinfecting water using aqueous extracts of medicinal plants. Seven medicinal plants used by Samburu herbalists for the treatment of stomach illnesses were investigated for water disinfection. Aqueous extracts of the dried powdered plant material were directly used to treat the water samples collected. Efficacy of water treatment with medicinal plants expressed as percentage reduction in bacterial colonies revealed that Acacia nilotica extract with a mean percentage reduction of 99.86% was the most effective at reducing the number of bacterial colonies. Albizia anthelmintica extract with a mean of 9.47% was the least effective at reducing the number of bacterial colonies. The study also revealed a possible interaction between plant extracts and water source (P<0.05, df=54). The results obtained in this study point out a possibility of using aqueous extracts from A. nilotica in disinfecting water of different physicochemical properties.

Point-of-use chlorination of turbid water: results from a field study in Tanzania

Household-based chlorine disinfection is widely effective against waterborne bacteria and viruses, and may be among the most inexpensive and accessible options for household water treatment. The microbiological effectiveness of chlorine is limited, however, by turbidity. In Tanzania, there are no guidelines on water chlorination at household level, and limited data on whether dosing guidelines for higher turbidity waters are sufficient to produce potable water. This study was designed to assess the effectiveness of chlorination across a range of turbidities found in rural water sources, following local dosing guidelines that recommend a 'double dose' for water that is visibly turbid. We chlorinated water from 43 sources representing a range of turbidities using two locally available chlorine-based disinfectants: WaterGuard and Aquatabs. We determined free available chlorine at 30 min and 24 h contact time. Our data suggest that water chlorination with WaterGuard or Aquatabs can be effective using both single and double doses up to 20 nephelometric turbidity units (NTU), or using a double dose of Aquatabs up to 100 NTU, but neither was effective at turbidities greater than 100 NTU.

Effectiveness of chlorine dispensers in emergencies: case study results from Haiti, Sierra Leone, Democratic Republic of Congo, and Senegal

Dispensers are a source-based water quality intervention with promising uptake results in development contexts. Dispenser programs include a tank of chlorine with a dosing valve that is installed next to a water source, a local Promoter who conducts community education and refills the Dispenser, and chlorine refills. In collaboration with response organizations, we assessed the effectiveness of Dispensers in four emergency situations. In the three initial and four sustained response phase evaluations, 70 Dispenser sites were visited, 2057 household surveys were conducted, and 1676 water samples were analyzed. Across the evaluations, reported Dispenser use ranged from 9 to 97%, confirmed Dispenser use (as measured by free chlorine residual) ranged from 5 to 87%, and effective use (as measured by improvement in household water quality to meet international standards) ranged from 0 to 81%. More effective Dispenser interventions installed Dispensers at point-sources, maintained a high-quality chlorine solution manufacturing and distribution chain, maintained Dispenser hardware, integrated Dispensers projects within larger water programs, remunerated Promoters, had experienced project staff, worked with local partners to implement the project, conducted ongoing monitoring, and had a project sustainability plan. Our results indicate that Dispensers can be, but are not always, an appropriate strategy to reduce the risk of waterborne diseases in emergencies.

Evaluation of semidecentralized emergency drinking water treatment

This study evaluates the potential for a novel semidecentralized approach that uses coagulant disinfectant products (CDPs) for humanitarian water treatment, by testing two commercially available products (CDP-W and CDP-T). Their performances were evaluated against the relevant water quality treatment objectives (The Sphere Project) under laboratory conditions, using a standardized testing protocol with both synthetic and natural surface test waters. Tests indicated a satisfactory performance by one of the products (CDP-W) with respect to humanitarian water quality objectives, (i.e., free chlorine residual, pH, and turbidity) that was dependent on initial water quality characteristics. Adequate bacterial inactivation (final thermotolerant coliform concentration of < 1 cfu/100 mL) was always attained and log reductions of up to 5 were achieved. The other product (CDP-T) did not exhibit any measurable coagulation and disinfection properties, indicating the variability of product quality and the need to conduct evaluations such as the ones presented in this study. Such results are of relevance to relief agencies delivering water supply interventions.

Household effectiveness vs. laboratory efficacy of point-of-use chlorination

Treatment of water at the household level offers a promising approach to combat the global burden of diarrheal diseases. In particular, chlorination of drinking water has been a widely promoted strategy due to persistence of residual chlorine after initial treatment. However, the degree to which chlorination can reduce microbial levels in a controlled setting (efficacy) or in a household setting (effectiveness) can vary as a function of chlorine characteristics, source water characteristics, and household conditions. To gain more understanding of these factors, we carried out an observational study within households in rural communities of northern coastal Ecuador. We found that the efficacy of chlorine treatment under controlled conditions was significantly better than its household effectiveness when evaluated both by ability to meet microbiological safety standards and by log reductions. Water treated with chlorine achieved levels of microbial contamination considered safe for human consumption after 24 h of storage in the household only 39-51% of the time, depending on chlorine treatment regimen. Chlorine treatment would not be considered protective against diarrheal disease according to WHO log reduction standards. Factors that explain the observed compromised effectiveness include: source water turbidity, source water baseline contamination levels, and in-home contamination. Water in 38% of the households that had low turbidity source water (<10 NTU) met the safe water standard as compared with only 17% of the households that had high turbidity source water (>10 NTU). A 10 MPN/100 mL increase in baseline Escherichia coli levels was associated with a 2.2% increase in failure to meet the E. coli standard. Higher mean microbial contamination levels were seen in 54% of household samples in comparison to their matched controls, which is likely the result of in-home contamination during storage. Container characteristics (size of the container mouth) did not influence chlorine effectiveness. We found no significant differences between chlorine treatment regimens in ability to meet the safe water standards or in overall log reductions, although chlorine dosage did modify the effect of source conditions. These results underscore the importance of measuring both source water and household conditions to determine appropriate chlorine levels, as well as to evaluate the appropriateness of chlorine treatment and other point-of-use water quality improvement interventions.

Effective use of household water treatment and safe storage in response to the 2010 Haiti earthquake

When water supplies are compromised during an emergency, responders often recommend household water treatment and safe storage (HWTS) methods, such as boiling or chlorination. We evaluated the near- and longer-term impact of chlorine and filter products distributed shortly after the 2010 earthquake in Haiti. HWTS products were deemed as effective to use if they actually improved unsafe household drinking water to internationally accepted microbiological water quality standards. The acute emergency survey (442 households) was conducted within 8 weeks of emergency onset; the recovery survey (218 households) was conducted 10 months after onset. Effective use varied by HWTS product (from 8% to 63% of recipients in the acute phase and from 0% to 46% of recipients in the recovery phase). Higher rates of effective use were associated with programs that were underway in Haiti before the emergency, had a plan at initial distribution for program continuation, and distributed products with community health worker support and a safe storage container.

Effects of temperature and pH on reduction of bacteria in a point-of-use drinking water treatment product for emergency relief

The effects of temperature and pH on the water treatment performance of a point-of-use (POU) coagulant/disinfectant product were evaluated. Cold temperatures (∼5°C) reduced the bactericidal efficiency of the product with regard to Escherichia coli and total coliform log(10) reductions.

Evaluation of the impact of the plastic BioSand filter on health and drinking water quality in rural Tamale, Ghana

A randomized controlled trial of the plastic BioSand filter (BSF) was performed in rural communities in Tamale (Ghana) to assess reductions in diarrheal disease and improvements in household drinking water quality. Few studies of household water filters have been performed in this region, where high drinking water turbidity can be a challenge for other household water treatment technologies. During the study, the longitudinal prevalence ratio for diarrhea comparing households that received the plastic BSF to households that did not receive it was 0.40 (95% confidence interval: 0.05, 0.80), suggesting an overall diarrheal disease reduction of 60%. The plastic BSF achieved a geometric mean reduction of 97% and 67% for E. coli and turbidity, respectively. These results suggest the plastic BSF significantly improved drinking water quality and reduced diarrheal disease during the short trial in rural Tamale, Ghana. The results are similar to other trials of household drinking water treatment technologies.

Use of household water treatment and safe storage methods in acute emergency response: case study results from Nepal, Indonesia, Kenya, and Haiti

Household water treatment (HWTS) methods, such as boiling or chlorination, have long been recommended in emergencies. While there is increasing evidence of HWTS efficacy in the development context, effectiveness in the acute emergency context has not been rigorously assessed. We investigated HWTS effectiveness in response to four acute emergencies by surveying 1521 targeted households and testing stored water for free chlorine residual and fecal indicators. We defined "effective use" as the percentage of the targeted population with contaminated household water who used the HWTS method to improve stored drinking water microbiological quality to internationally accepted levels. Chlorine-based methods were distributed in all four emergencies and filters in one emergency. Effective use ranged widely, from 0-67.5%, with only one pre-existing chlorine program in Haiti and unpromoted boiling use in Indonesia reaching >20%. More successful programs provided an effective HWTS method, with the necessary supplies and training provided, to households with contaminated water who were familiar with the method before the emergency. HWTS can be effective at reducing the risk of unsafe drinking water in the acute emergency context. Additionally, by focusing on whether interventions actually improve drinking water quality in vulnerable households, "effective use" provides an important program evaluation metric.

Inactivation and sub-lethal injury of salmonella typhi, salmonella typhimurium and vibrio cholerae in copper water storage vessels

Background

This study provides information on the antibacterial effect of copper against the water-borne pathogens Salmonella Typhi, Salmonella Typhimurium and Vibrio cholerae.

Methods

Suspensions of each pathogen were kept in water within a traditional copper vessel at 30°C for 24 h. Samples were withdrawn, diluted and plated onto suitable growth media. Conventional enumeration of healthy (uninjured) bacteria was carried out using standard aerobic incubation conditions. Additionally, reactive oxygen species-neutralised (ROS-n) conditions were achieved by adding the peroxide scavenger sodium pyruvate to the medium with anaerobic incubation, to enumerate uninjured (ROS-insensitive) and injured (ROS-sensitive) bacteria. Differences between log-transformed means of conventional (aerobic) and ROS-n counts were statistically evaluated using t tests.

Results

Overall, all three pathogens were inactivated by storage in copper vessels for 24 h. However, for shorter-term incubation (4-12 h), higher counts were observed under ROS-n conditions than under aerobic conditions, which demonstrate the presence of substantial numbers of sub-lethally injured cells prior to their complete inactivation.

Conclusions

The present study has for the first time confirmed that these bacterial pathogens are inactivated by storage in a copper vessel within 24 h. However, it has also demonstrated that it is necessary to account for short-term sub-lethal injury, manifest as ROS-sensitivity, in order to more fully understand the process. This has important practical implications in terms of the time required to store water within a copper vessel to completely inactivate these bacteria and thereby remove the risk of water-borne disease transmission by this route.

Evaluation of human enteric viruses in surface water and drinking water resources in southern Ghana

An estimated 884 million people worldwide do not have access to an improved drinking water source, and the microbial quality of these sources is often unknown. In this study, a combined tangential flow, hollow fiber ultrafiltration (UF), and real-time PCR method was applied to large volume (100 L) groundwater (N = 4), surface water (N = 9), and finished (i.e., receiving treatment) drinking water (N = 6) samples for the evaluation of human enteric viruses and bacterial indicators. Human enteric viruses including norovirus GI and GII, adenovirus, and polyomavirus were detected in five different samples including one groundwater, three surface water, and one drinking water sample. Total coliforms and Escherichia coli assessed for each sample before and after UF revealed a lack of correlation between bacterial indicators and the presence of human enteric viruses.

Biochemical evidence of efficacy of potash alum for the control of dengue vector Aedes aegypti (Linnaeus)

Aedes aegypti is the primary vector of dengue, yellow fever and chikungunya in India and other South East Asian countries, and novel insecticides for vector control are urgently needed. In the present investigation, efficacy of potash alum, a traditionally known double salt in Indian and Chinese medicine system, was tested against the larvae of dengue vector, A. aegypti. LC(50,) LC(90) and LC(99) values were recorded for various instar larvae where I instar larvae were found to be the most susceptible and IV instar larvae as the least susceptible one. The LC(50) values of crude and standard potash alum of various instar larvae ranged between 15.29 and 48.53 ppm and 20.50-65.10 ppm, respectively. Biochemical changes were also evidenced in IV instar A. aegypti larvae following a sublethal exposure for 24 h in the levels of various nutrient reserves and primary metabolites such as sugar, glycogen, lipids and proteins suggesting possible mode of action responsible for larval mortality. Sugar and glycogen concentrations were measured as 24.6 and 10.67 μg per five larvae in controls which were significantly (p<0.05) reduced by 32.11-93.98% and 39.26-94.47%, respectively, in larvae treated with crude alum. In controls, protein and lipid content were recorded as 210.74 and 94.71 μg per five larvae which dropped up to 26.53% and 25.5%, respectively, in larvae following treatment with crude alum. Moreover, drastic changes were also recorded for DNA content with 25.39-44.17% decrease in crude alum-treated larvae. It is evident from these results that potash alum, a fairly cheaper and readily available ecofriendly compound could be recommended as a potential chemical larvicide against dengue vector at mosquito breeding sites in the vicinity of human dwellings.

Mosquito larvicidal potential of potash alum against malaria vector Anopheles stephensi (Liston)

Mosquito larviciding may prove to be an effective tool for incorporating into integrated vector management strategies for reducing malaria transmission. Here, we report the potential of potash alum, a traditionally known salt in Indian Ayurveda and Chinese medicine system, in malaria vector control by evaluating its aqueous suspension as larvicide and growth disruptor of Anopheles stephensi, under laboratory conditions. Immature stages of the mosquito were tested using WHO guidelines. 50 and 90% lethal concentrations among various larvae ranged between 2.1 to 48.74 ppm and 15.78 to 93.11 ppm, respectively. The results indicated that larvicidal effects of potash alum were comparable to various biological and chemical insecticides. The study provides considerable scope in exploiting local indigenous resources for the control of nuisance mosquito vectors.

Solar disinfection of drinking water in the prevention of dysentery in South African children aged under 5 years: the role of participant motivation

Solar disinfection (SODIS) effectively improves the microbial quality of drinking water for preventing diarrhea; however, the effect of participant motivation has not been studied. This 1-year randomized controlled trial investigated the effect of SODIS of drinking water and motivation on the incidence of dysentery and nondysentery diarrhea among children of age 6 months to 5 years living in periurban communities in South Africa.We compared 383 children in 297 households using SODIS with 335 children in 267 households with no intervention. At baseline 62.4% of the study households had stored water which met World Health Organization guidelines for zero thermotolerant coliforms per 100 mL. Dysentery was recorded using a pictorial diary. Incidence of dysentery was significantly associated with higher motivation, defined as 75% or better completion of diarrhea data. Incidence rates were lower in those drinking solar disinfected water (incidence rate ratio 0.64, 95% CI 0.39 - 1.0, P = 0.071) but not statistically significant. Compared with the control, participants with higher motivation achieved a significant reduction in dysentery (incidence rate ratio 0.36, 95% CI 0.16 - 0.81, P = 0.014). However, there was no significant reduction in risk at lower levels of motivation. Solar disinfection was not significantly associated with nondysentery diarrhea risk overall (P = 0.419). A statistically significant reduction in dysentery was achieved only in households with higher motivation, showing that motivation is a significant determinant for measurable health gains. Failure of three-quarters of participants to achieve a significant reduction in dysentery suggests that research into effective implementation is required.

Determinants of use of household-level water chlorination products in rural Kenya, 2003-2005

Household-level water treatment products provide safe drinking water to at-risk populations, but relatively few people use them regularly; little is known about factors that influence uptake of this proven health intervention. We assessed uptake of these water treatments in Nyanza Province, Kenya, November 2003–February 2005. We interviewed users and non-user controls of a new household water treatment product regarding drinking water and socioeconomic factors. We calculated regional use-prevalence of these products based on 10 randomly selected villages in the Asembo region of Nyanza Province, Kenya. Thirty-eight percent of respondents reported ever using household-level treatment products. Initial use of a household-level product was associated with having turbid water as a source (adjusted odds ratio [AOR] = 16.6, p = 0.007), but consistent usage was more common for a less costly and more accessible product that did not address turbidity. A combination of social marketing, retail marketing, and donor subsidies may be necessary to extend the health benefits of household-level water treatment to populations most at risk.

Disinfection by-product formation and mitigation strategies in point-of-use chlorination with sodium dichloroisocyanurate in Tanzania

Almost a billion persons lack access to improved drinking water, and diarrheal diseases cause an estimated 1.87 million deaths per year. Sodium dichloroisocyanurate (NaDCC) tablets are widely recommended for household water treatment to reduce diarrhea. Because NaDCC is directly added to untreated water sources, concerns have been raised about the potential health impact of disinfection by-products. This study investigated trihalomethane (THM) production in water from six sources used for drinking (0.6-888.5 nephelometric turbidity units) near Arusha, Tanzania. No sample collected at 1, 8, and 24 hours after NaDCC addition exceeded the World Health Organization guideline values for either individual or total THMs. Ceramic filtration, sand filtration, cloth filtration, and settling and decanting were not effective mitigation strategies to reduce THM formation. Chlorine residual and THM formation were not significantly different in NaDCC and sodium hypochlorite treatment. Household chlorination of turbid and non-turbid waters did not create THM concentrations that exceeded health risk guidelines.

End-user preferences for and performance of competing POU water treatment technologies among the rural poor of Kenya

Household point-of-use (POU) water treatment technologies targeted at vulnerable populations are microbiologically effective and, in small trials, improve health. We do not understand the factors that influence preference for and adoption of these technologies by target end-users. We cycled 400 rural subsistence farm households in western Kenya through three randomly ordered two-month trials of three POU products: dilute hypochlorite solution, porous ceramic filtration, and a combined flocculant-disinfectant powdered mixture to compare relative end-user preferences and usage. Households reported higher usage of both dilute hypochlorite and filters than the flocculant-disinfectant. Averaged among all participating households, Escherichia coli reductions in treated water were generally higher among those that received dilute hypochlorite solution than among those receiving either of the other two products. Among those households that self-reported product usage, the E. coli reductions achieved by dilute hypochlorite and the flocculant-disinfectant are statistically equivalent to one another and higher than the reductions achieved by filters. At the same time, households ranked filters most frequently as their most preferred product.

Chlorination and water quality monitoring within a public drinking water supply in Rawalpindi Cantt (Westridge and Tench) area, Pakistan

Concern over the presence of fecal coliform in public drinking water supplies has been expressed in recent years in Pakistan since it has been regarded as pathogenic organism of prime importance in gastroenteritis. Two major drinking water distribution systems in the Cantt area of Rawalpindi district covering the Westridge and Tench areas was monitored over a 2-month period to determine the prevalence of fecal coliform and chlorine residual. The collected samples were examined for total chlorine, free chlorine residual, chloramines, total coliforms, fecal coliforms, and turbidity. The drinking water quality monitoring in the distribution network was performed by collecting samples from water source, overhead reservoir, and residential taps. In the Westridge area, total chlorine varied from the lowest value of 0.27 mg/L at Station # W-5 to the highest value of 0.42 mg/L at Station # W-2, total coliforms varied from 1.1 to 3.6 most probable number (MPN)/100 mL with presence of Escherichia coli in all samples, total dissolved solids (TDS) ranged from 199.5 to 205 mg/L, conductivity fluctuated between 399 and 411 microS/cm, and turbidity varied from 0.43 to 0.73 NTU. In the Tench area, the value of total chlorine ranged from 0.14 mg/L at Station # T-7 to 0.55 mg/L at Station # T-1. Total coliform varied from 3.6 to 5.1 MPN/100 mL and fecal coliform were detected at all the stations except at Station # T-1. TDS ranged from 201.4 to 257 mg/L, conductivity varied from 343 to 513 microS/cm, and turbidity ranged between 0.66 and 1.55 NTU. It is recommended to the respective agencies to ensure that the chlorine residual is available at consumer end.

Comparison of point-of-use technologies for emergency disinfection of sewage-contaminated drinking water

Four point-of-use disinfection technologies for treating sewage-contaminated well water were compared. Three systems, based on flocculant-disinfectant packets and N-halamine chlorine and bromine contact disinfectants, provided a range of 4.0 to >6.6 log(10) reductions (LR) of naturally occurring fecal indicator and heterotrophic bacteria and a range of 0.9 to >1.9 LR of coliphage.

Performance of microbiological control by a point-of-use filter system for drinking water purification

Purification capacity of a faucet mounted type water filter for home use was evaluated, particularly with regard to microbiological performance under different running conditions. Biofilms were formed inside the filter, affecting the bacterial quality of the effluent water. Low flow rate, long stagnation period and high filter temperature were found favorable for bacterial growth inside. By commercial analytical profile index (API) kits, ten different bacterial species were identified in drinking water, four of which were probably contributed to the biofilm formation since they were also present in the biofilm. Fluorescence in situ hybridization (FISH) was used to confirm the API identification results, and direct viable count (DVC) method was employed to improve the sensitivity of FISH for the isolated Acinetobacter spp. and Pseudomonas putida as models. Relationship between the filter operating condition and the bacterial community alteration was partly revealed, which could provide the basic knowledge for the filter design and its practical use.

Diarrhoea prevention in a high-risk rural Kenyan population through point-of-use chlorination, safe water storage, sanitation, and rainwater harvesting

Lack of access to safe water and sanitation contributes to diarrhoea moribidity and mortality in developing countries. We evaluated the impact of household water treatment, latrines, shallow wells, and rainwater harvesting on diarrhoea incidence in rural Kenyan children. We compared diarrhoea rates in 960 children aged <5 years in 556 households in 12 randomly selected intervention villages and six randomly selected comparison villages during weekly home visits over an 8-week period. On multivariate analysis, chlorinating stored water [relative risk (RR) 0.44, 95% confidence interval (CI) 0.28-0.69], latrine presence (RR 0.71, 95% CI 0.54-0.92), rainwater use (RR 0.70, 95% CI 0.52-0.95), and living in an intervention village (RR 0.31, 95% CI 0.23-0.41), were independently associated with lower diarrhoea risk. Diarrhoea risk was higher among shallow well users (RR 1.78, 95% CI 1.12-2.83). Chlorinating stored water, latrines, and rainwater use all decreased diarrhoea risk; combined interventions may have increased health impact.

Point-of-use water treatment and diarrhoea reduction in the emergency context: an effectiveness trial in Liberia

Communicable diseases are of particular concern in conflict and disaster-affected populations that reside in camp settings. In the acute emergency phase, diarrhoeal diseases have accounted for more than 40% of deaths among camp residents. Clear limitations exist in current water treatment technologies, and few products are capable of treating turbid water. We describe the findings of a 12-week effectiveness study of point-of-use water treatment with a flocculant-disinfectant among 400 households in camps for displaced populations in Monrovia, Liberia. In intervention households, point-of-use water treatment with the flocculant-disinfectant plus improved storage reduced diarrhoea incidence by 90% and prevalence by 83%, when compared with control households with improved water storage alone. Among the intervention group, residual chlorine levels met or exceeded Sphere standards in 85% (95% CI: 83.1-86.8) of observations with a 95% compliance rate.

Microbiological performance of a water treatment unit designed for household use in developing countries

Interventions to improve water quality, particularly when deployed at the household level, are an effective means of preventing endemic diarrhoeal disease, a leading cause of mortality and morbidity. Following a national survey indicating widespread faecal contamination of drinking water in Indian cities, a point-of-use water treatment unit was developed, which combines filtration and disinfection, does not require power or water pressure and has an operating cost of Rs. 0.25 (US$0.0057) per litre. We assessed the microbiological performance of the unit in the laboratory over the full 1500 l design life of the unit's consumable components. Geometric mean reductions for the units were more than 6 logs (99.9999%) for bacteria, more than 7 logs (99.99999%) for viruses and more than 3 logs (99.9%) for the test surrogate for protozoan cysts. Geometric mean reductions exceeded levels established for microbial water purifiers. The product water was free of detectable chlorine. If these results are validated in field trials, the deployment of the unit on a wide scale among vulnerable populations may make an important contribution to public health efforts to control intractable waterborne diseases.

Preventing diarrhoea with household ceramic water filters: assessment of a pilot project in Bolivia

In an attempt to prevent diarrhoea in a rural community in central Bolivia, an international non-governmental organization implemented a pilot project to improve drinking water quality using gravity-fed, household-based, ceramic water filters. We assessed the performance of the filters by conducting a five-month randomized controlled trial among all 60 households in the pilot community. Water filters eliminated thermotolerant (faecal) coliforms from almost all intervention households and significantly reduced turbidity, thereby improving water aesthetics. Most importantly, the filters were associated with a 45.3% reduction in prevalence of diarrhoea among the study population (p = 0.02). After adjustment for household clustering and repeated episodes in individuals and controlling for age and baseline diarrhoea, prevalence of diarrhoea among the intervention group was 51% lower than controls, though the protective effect was only borderline significant (OR 0.49, 95% CI: 0.24, 1.01; p = 0.05). A follow-up survey conducted approximately 9 months after deployment of the filters found 67% being used regularly, 13% being used intermittently, and 21% not in use. Water samples from all regularly used filters were free of thermotolerant coliforms.

Sodium dichloroisocyanurate (NaDCC) tablets as an alternative to sodium hypochlorite for the routine treatment of drinking water at the household level

Household water treatment using sodium hypochlorite (NaOCl) has been recognized as a cost-effective means of reducing the heavy burden of diarrhea and other waterborne diseases, especially among populations without access to improved water supplies. Sodium dichloroisocyanurate (NaDCC), which is widely used in emergencies, is an alternative source of chlorine that may present certain advantages over NaOCl for household-based interventions in development settings. We summarize the basic chemistry and possible benefits of NaDCC, and review the available literature concerning its safety and regulatory treatment and microbiological effectiveness. We review the evidence concerning NaDCC in field studies, including microbiological performance and health outcomes. Finally, we examine studies and data to compare NaDCC with NaOCl in terms of compliance, acceptability, affordability and sustainability, and suggest areas for further research.

Inactivation of Escherichia coli and coliform bacteria in traditional brass and earthernware water storage vessels

The detection and enumeration of indicator bacteria such as Escherichia coli is used to assess the extent of faecal contamination of drinking water. On the basis of this approach, the effectiveness of storing water contaminated with faecal indicator bacteria in brass or earthern vessels (mutkas) of the type used in rural India have been investigated. Suspensions of bacteria in sterile distilled water were maintained for up to 48 h in each vessel and enumerated by surface plate counts on nutrient agar (non-selective) and several selective coliform media at 37 degrees C either under standard aerobic conditions, or under conditions designed to neutralise reactive oxygen species (ROS), e.g. using an anaerobic cabinet to prepare plates of pre-reduced growth medium or by inclusion of sodium pyruvate in the growth medium, with incubation of aerobically-prepared plates in an anaerobic jar. The counts obtained for E. coli decreased on short-term storage in a brass mutka; counts for selective media were lower than for equivalent counts for non-selective medium, with ROS-neutralised conditions giving consistently higher counts than aerobic incubation. However, after 48 h, no bacteria were cultivable under any conditions. Similar results were obtained using water from environmental sources in the Panjab, and from rural households where brass and earthern mutkas are used for storage of drinking water, with enumeration on selective coliform media (presumptive total coliforms). In all cases results indicated that, while storage of water in a brass mutka can inactivate E. coli and coliforms over a 48 h period, standard aerobic plate counting using selective media may not be fully effective in enumerating sub-lethally damaged bacteria.

Influence of solid dairy manure and compost with and without alum on survival of indicator bacteria in soil and on potato

We measured Escherichia coli, Enterococcus spp. and fecal coliform numbers in soil and on fresh potato skins after addition of solid dairy manure and dairy compost with and without alum (Al(2)(SO(4))(3)) treatment 1, 7, 14, 28, 179 and 297 days after application. The addition of dairy compost or solid dairy manure at rates to meet crop phosphorus uptake did not consistently increase E. coli and Enterococcus spp. and fecal coliform bacteria in the soil. We did not detect E. coli in any soil sample after the first sampling day. Seven, 14, 28, 179 and 297 days after solid dairy waste and compost and alum were applied to soil, alum did not consistently affect Enterococcus spp. and fecal coliform bacteria in the soil. We did not detect E. coli in any soil, fresh potato skin or potato wash-water at 214 days after dairy manure or compost application regardless of alum treatment. Dairy compost or solid dairy manure application to soil at rates to meet crop phosphorus uptake did not consistently increase Enterococcus spp. and fecal coliform numbers in bulk soil. Solid dairy manure application to soil at rates to meet crop phosphorus uptake, increased Enterococcus spp. and fecal coliform numbers in potato rhizosphere soil. However, fresh potato skins had higher Enterococcus spp. and fecal coliform numbers when solid dairy manure was added to soil compared to compost, N and P inorganic fertilizer and N fertilizer treatments. We did not find any E. coli, Enterococcus or total coliform bacteria on the exterior of the tuber, within the peel or within a whole baked potato after microwave cooking for 5 min.

Household based treatment of drinking water with flocculant-disinfectant for preventing diarrhoea in areas with turbid source water in rural western Kenya: cluster randomised controlled trial

OBJECTIVE

To compare the effect on prevalence of diarrhoea and mortality of household based treatment of drinking water with flocculant-disinfectant, sodium hypochlorite, and standard practices in areas with turbid water source in Africa.

DESIGN

Cluster randomised controlled trial over 20 weeks.

SETTING

Family compounds, each containing several houses, in rural western Kenya.

PARTICIPANTS

6650 people in 605 family compounds.

INTERVENTION

Water treatment: flocculant-disinfectant, sodium hypochlorite, and usual practice (control).

MAIN OUTCOME MEASURES

Prevalence of diarrhoea and all cause mortality. Escherichia coli concentration, free residual chlorine concentration, and turbidity in household drinking water as surrogates for effectiveness of water treatment.

RESULTS

In children < 2 years old, compared with those in the control compounds, the absolute difference in prevalence of diarrhoea was -25% in the flocculant-disinfectant arm (95% confidence interval -40 to -5) and -17% in the sodium hypochlorite arm (-34 to 4). In all age groups compared with control, the absolute difference in prevalence was -19% in the flocculant-disinfectant arm (-34 to -2) and -26% in the sodium hypochlorite arm (-39 to -9). There were significantly fewer deaths in the intervention compounds than in the control compounds (relative risk of death 0.58, P = 0.036). Fourteen per cent of water samples from control compounds had E coli concentrations < 1 CFU/100 ml compared with 82% in flocculant-disinfectant and 78% in sodium hypochlorite compounds. The mean turbidity of drinking water was 8 nephelometric turbidity units (NTU) in flocculant-disinfectant households, compared with 55 NTU in the two other compounds (P < 0.001).

CONCLUSIONS

In areas of turbid water, flocculant-disinfectant was associated with a significant reduction in diarrhoea among children < 2 years. This health benefit, combined with a significant reduction in turbidity, suggests that the flocculant-disinfectant is well suited to areas with highly contaminated and turbid water.