No description available.

Lead and copper in drinking water are known to pose aesthetic and health concerns for humans and pets. The United States Environmental Protection Agency (US EPA) Lead and Copper Rule (LCR) set 90th percentile action levels for lead (15 ppb) and copper (1.3 mg/L), above which utilities must implement systemwide corrosion control. However, gaps in the US EPA LCR leave at least 10% of residents using municipal water and all private well users vulnerable to elevated lead and copper in their drinking water. To help address these gaps in the LCR, this dissertation 1) Evaluates accuracy of at-home lead in water test kits to help residents identify lead problems, 2) Refines orthophosphate corrosion control guidance to help reduce cuprosolvency, 3) Identifies challenges to mitigating cuprosolvency by raising pH, and 4) Develops guidance that can help residents assess and address cuprosolvency problems. Lead in drinking water can pose a variety of health concerns, particularly for young children. The revised LCR will still leave many residents unprotected from elevated lead in their drinking water and potentially wondering what to do about it. Many consumers concerned about lead may choose to purchase at-home lead in water test kits, but there is no certification authority to ensure their accuracy. Most off-the-shelf tests purchased in this work (12 of 16) were not able to detect dissolved or particulate lead at levels of concern in drinking water (i.e. near the lead action level of 15 ppb) due to high detection limits (5,000-20,000 ppb). Binary type tests, which indicate the presence or absence of lead based on a trigger threshold of 15 ppb, were often effective at detecting dissolved lead, but they failed to detect the presence of leaded particles that often cause high lead exposures in drinking water problems. Some of these problems detecting particles could be reduced using simple at-home acid dissolution with weak household acids such a vinegar or lemon juice. Our analysis points out the strengths and weaknesses of various types of at-home lead in water tests, which could be particularly important considering potential distrust in official results in the aftermath of the Flint Water Crisis. Elevated cuprosolvency, or copper release into drinking water, can be an aesthetic concern due to fixture staining, blue water, and green hair and can pose health concerns for residents and pets. In addition to the general gaps in the LCR described above, compliance sampling in the LCR focuses on older homes at highest risk of elevated lead, rather than the newer homes at highest risk of elevated copper. Problems with elevated copper can sometimes go undetected as a result. Guidance was developed to help proactive utilities address cuprosolvency issues through the addition of orthophosphate corrosion inhibitors or pH adjustment as a function of a water's alkalinity. Linear regressions developed from pipe cuprosolvency tests (R2>0.98) determined a "minimum" orthophosphate dose or a "minimum" pH for a given alkalinity that was expected to almost always reduce copper below the 1.3 mg/L EPA action level in a reasonable length of time. The subjective nature of the terms "almost always" and "reasonable length of time" were quantitatively discussed based on laboratory and field data. Orthophosphate addition was generally very effective at cuprosolvency control. Orthophosphate treatment in copper tube cuprosolvency tests produced cuprosolvency below the action level within the first week of treatment. As expected, orthophosphate treated waters sometimes resulted in higher long-term cuprosolvency than the same waters without orthophosphate corrosion control treatment. This is consistent with the formation of phosphate scales which have an intermediate solubility between the cupric hydroxide in new pipes and the malachite or tenorite scales expected in pipe aging without orthophosphate. A linear regression (R2>0.98) was used to determine the orthophosphate dose needed for a given alkalinity to yield copper below the 1.3 mg/L action level in the pipe segments with the highest, 2nd highest, 3rd highest copper concentrations (100th, 95th, or 90th percentile, n=20 replicates, five each from four manufacturers) after 4 or 22 weeks of pipe aging. This regression was generally in good agreement with a bin approach put forth in the 2015 Consensus Statement from the National Drinking Water Advisory Council, but in some cases the regression predicted that higher orthophosphate doses would be needed. In contrast, due to the greater complexity of the reactions involved, a similar simplistic approach for pH adjustment is not widely applicable. A linear regression predicted that higher "minimum" pH values would be needed to control cuprosolvency compared to those suggested by the 2015 National Drinking Water Advisory Consensus Statement. Results indicate that factors such as the potential for calcite precipitation, pipe age, and significant variability in cuprosolvency from pipes of different manufacturers may warrant further research. Field LCR monitoring data indicated that 90th percentile copper concentrations continued to decline over a period of years or decades when orthophosphate is not used, and our laboratory results demonstrate a few cases where copper levels even increased with time. Consideration of confounding effects from other water quality parameters such as natural organic matter, silica, and sulfate would be necessary before the "minimum" pH criteria could be broadly applied. Guidance was then developed to help address cuprosolvency issues on a single building or single home basis for residents with private wells or those with high copper in municipal systems meeting the LCR. A hierarchy of costs and considerations for various interventions are discussed including replumbing with alternative materials, using bottled water or point use pitcher, tap, or reverse osmosis filters to reduce copper consumption, and using whole house interventions like more conventional orthophosphate addition and pH adjustment, or unproven strategies like granular activated carbon filtration, reverse osmosis treatment, and ion exchange treatment. Laboratory and citizen science testing demonstrated that some inexpensive at-home tests for pH and copper, were accurate enough to serve as inputs for this guidance and could empower consumers to diagnose their problems and consider possible solutions. Citizen science field testing and companion laboratory studies of potential interventions indicate that short-term (<36 weeks) use of pH adjustment, granular activated carbon, anion exchange and reverse osmosis treated water were not effective at forming a protective scale for the resident's water tested. In this case-study, cuprosolvency problems were ultimately related to water chemistry and linked to variability in influent water pH. Overall, this work highlighted weaknesses in the current US EPA Lead and Copper Rule. It attempted to close some of these gaps by assessing the accuracy of at-home citizen science tests for lead and copper detection and developing guidance to support voluntary interventions by utilities or consumers. Ideally, local authorities (utilities, health departments, cooperative extension programs) could adapt this guidance to account for local water quality considerations and support consumers in resolving cuprosolvency issues. This guidance may also serve as a citizen science approach that some consumers could use to make decisions on their own. Future work could extend and improve on these initial efforts. / Doctor of Philosophy / Lead or copper in drinking water can come from corrosion of plumbing materials. Elevated levels of these metals can cause aesthetic concerns like blue water and fixture staining, as well as health concerns for humans and pets. The United States Environmental Protection Agency (US EPA) Lead and Copper Rule (LCR) is designed to address system wide lead and copper corrosion problems in municipal water supplies. According to the LCR, utilities must notify consumers and implement corrosion control if more than 10% of homes sampled have lead above 15 ppb or copper above 1.3 mg/L. However, gaps in the US EPA LCR leave at least 10% of residents using municipal water and all private well users vulnerable to elevated lead and copper in their drinking water. To help address these gaps in the LCR, this dissertation 1) Evaluates how accurate residential at-home tests are at detecting lead in water, 2) Refines orthophosphate corrosion control guidance to help address elevated cuprosolvency (i.e. copper release to water), 3) Identifies challenges addressing cuprosolvency issues by raising the pH, and 4) Develops guidance to help residents detect and address cuprosolvency problems. Lead in drinking water can come from corrosion of lead bearing plumbing such as lead service lines and lead solder. Lead can pose a variety of health concerns, particularly for young children. In spite of recent revisions, the LCR will still leave many residents unprotected from elevated lead in their drinking water and potentially wondering what to do about it. Many consumers concerned about lead may choose to purchase at-home lead in water test kits, but there is no certification authority to ensure that they are accurate. Most off- the-shelf tests purchased in this work (12 of 16) were not able to detect dissolved lead or lead from particulate at concentrations expected to occur in drinking water due to high detection limits (5,000-20,000 ppb). Binary type tests, which indicate the presence or absence of lead based on a trigger threshold of 15 ppb, were often effective at detecting dissolved lead, but they failed to detect the presence of leaded particles that often cause high lead exposures in drinking water problems. Some of these problems detecting particles could be reduced using a simple procedure to attempt to dissolve the particles using weak household acids like vine- gar or lemon juice. Our analysis points out the strengths and weaknesses of various types of at-home lead in water tests, which could be particularly important considering potential distrust in official results in the aftermath of the Flint Water Crisis. Elevated cuprosolvency, or copper release into drinking water, primarily causes aesthetic problems like fixture staining and blue water, and it can also pose acute and serious health concerns for residents and some pets. Many of the same issues with the LCR that leave residents at risk of lead can also lead to unaddressed issues with elevated copper. In addition to those issues, the LCR focuses on collecting water samples in older homes at highest risk of lead, instead of newer homes at highest risk of copper. This means that many cuprosolvency problems could go undetected. Guidance was developed to help proactive utilities address cuprosolvency problems throughout the whole water system by adding orthophosphate corrosion inhibitors or adjusting the pH of their water. Linear relationships were developed from cuprosolvency testing in copper pipes (strong correlations, R2>0.98) to determine the "minimum" orthophosphate dose or pH value needed based on the water alkalinity that was expected to almost always reduce copper below the 1.3 mg/L EPA action level in a reason- able length of time. We also discuss the subjective nature of the terms "almost always" and "reasonable length of time" based on laboratory and field data. Adding orthophosphate was generally very effective at controlling cuprosolvency. In tests in copper pipe segments, copper concentrations in the water were below the action level within one week of starting to add orthophosphate. As expected, sometimes waters with orthophosphate treatment resulted in higher long-term copper concentrations than waters without orthophosphate. This is in agreement with reports of formation of phosphate mineral scales which have an intermediate solubility between those in new pipes and the scales expected in pipe aging without orthophosphate. A linear regression (strong correlation, R2>0.98) was used to determine the orthophosphate dose needed for a given alkalinity to yield copper below the 1.3 mg/L action level in the worst, second worst, and third worst pipes of the 20 pipe segments tested (100th, 95th, or 90th percentile) after 4 or 22 weeks of pipe aging. This linear relationship was generally in good agreement with a bin approach put forth in the 2015 Consensus Statement from the National Drinking Water Advisory Council, but in some cases the regression predicted that higher orthophosphate doses would be needed. In contrast, we showed that adjusting the pH to control cuprosolvency was too simplistic to be widely applicable because the chemical reactions involved are more complex. The linear relationship we developed predicted that higher "minimum" pH values would be needed to control cuprosolvency compared to those suggested by the 2015 National Drinking Water Advisory Consensus Statement. Other factors such as the potential calcite precipitation, which can clog pipes, pipe age, and significant variability in copper coming off pipes from different manufacturers may require consideration when considering treatment options. LCR monitoring data from utilities indicated that copper concentrations continued to decline over a period of years or decades when orthophosphate was not used, and our laboratory results demonstrate a few cases where copper levels even increased with time. We also showed that other water quality components like natural organic matter, silica, and sulfate can affect cuprosolvency and could make it difficult to broadly apply the "minimum" pH approach for controlling cuprosolvency in places with different water qualities. Guidance was then developed to help address cuprosolvency issues on a single building or single home basis for residents with private wells or those with high copper in municipal systems meeting the LCR. A hierarchy of costs and considerations is described for various interventions including replumbing with alternative materials, using bottled water or point use pitcher, tap, or reverse osmosis filters to reduce copper consumption, and using whole house interventions like more conventional orthophosphate addition and pH adjustment, or unproven strategies like granular activated carbon filtration, reverse osmosis treatment, and ion exchange treatment. Laboratory and citizen science testing demonstrated that some in- expensive at-home tests for pH and copper, were accurate enough to serve as inputs for this guidance and could empower consumers to diagnose their problems and consider possible solutions. Testing of potential water treatments in the laboratory and citizen science testing in a resident's home showed that short-term (<36 weeks) use of pH adjustment, granular activated carbon, anion exchange, and reverse osmosis treated water did not form a permanent, low-solubility protective scale for this resident's water. In this case-study, cuprosolvency problems were ultimately related to water chemistry and linked to variability in incoming pH of the water. This thesis highlighted weaknesses in the current US EPA Lead and Copper Rule. It at- tempted to address some of these issues by determining the accuracy of at-home citizen science tests to help residents detect lead and copper and developing guidance to support voluntary interventions by utilities or consumers. Ideally, local authorities (utilities, health departments, cooperative extension programs) could adapt this guidance to account for local water quality considerations and support consumers in resolving cuprosolvency issues. This guidance may also serve as a citizen science approach that some consumers could use to make decisions on their own. Future work could extend and improve on these initial efforts.

Despite claims of nearly 100% access to potable drinking water in the US, issues of drinking water quality, accessibility, and equity persist in many regions of the country. Drinking water is a common health concern in rural communities, where social, geographic, and economic challenges can inhibit the provision of reliable municipal water. Households without access to municipal water often rely on private wells, which are solely the responsibility of the homeowner to test, treat, and maintain, or roadside springs. These water sources often do not employ water treatment and users can therefore be uniquely susceptible to environmental contaminants. The goal of this research was to examine point-of-use (POU) treatment options that can be used by individuals to improve their drinking water quality and reduce exposure to common contaminants prior to consumption. Two drops (~0.10 mL) of unscented, household bleach in one gallon of spring water is a simple, low-cost treatment option that successfully inactivates total coliform and E. coli and provides an appropriate free chlorine residual (> 0.5 mg/L) over a 1-month time period, without exceeding free chlorine taste thresholds (< 2 mg/L). Efforts to distribute information on this disinfection protocol to spring users in southern West Virginia and southwestern Virginia were well-received; however, only 60% of surveyed spring users report that they plan to implement the protocol. POU faucet filters have been successfully implemented in homes reliant on municipal water to reduce metal contaminant levels in drinking water. Few studies have assessed the effectiveness of these filters in improving water quality in homes reliant on private wells. Faucet-mounted POU filters distributed to homes reliant on private wells in Virginia and southern West Virginia statistically significantly lowered levels of Ba, Cd, Cr, Total Coliform, U, Cu, Pb, Al, Fe, Mn, Zn, and Sr in tap water. However, levels of many contaminants of interest still exceeded at least one Safe Drinking Water Act regulation/recommendation in several filtered samples. Additionally, less than half of study participants reported that they liked using the filters with several citing issues with flowrate. Faucet-mounted POU filters can also be a useful tool in assessing exposure to contaminants at the tap. The acid flow-through method of metals recovery has previously proven to be successful in recovering dissolved Pb from dosed filters. In this study, the acid flow-through extraction method was applied to water spiked with high or low levels of Pb, Fe, or Cu. While faucet-mounted activated carbon filters successfully removed Pb and Cu from dosed influent (>91% removal), filter behavior under influent Fe concentrations of greater than 300 ppb was extremely variable. The acid flow-through method of metals extraction provided some recovery from filters dosed with high and low concentrations of Pb (38.9-70.4%). Recovery of Cu and Fe was variable, likely in part due to Fe and Cu leaching from filter media, suggesting that alternative methods of metals extraction and recovery from POU faucet filters dosed with Fe and Cu, or other common water contaminants (e.g., As, Ba, Cd), must be explored. While POU treatment can be useful in improving drinking water quality in rural households, limitations to adoption persist and must be addressed along with efforts to protect drinking water quality in homes in a more permanent, sustainable way. / Doctor of Philosophy / Drinking water quality is a common health concern in rural communities, where social, geographic, and economic challenges can make municipal water quality unreliable. Households without access to municipal water often use private wells and sometimes roadside springs for drinking water. These water sources are often untreated which can expose users to environmental contaminants such as bacteria or metals. The goal of this research was to study point-of-use (POU) treatment options that can be used by individuals looking to improve their drinking water quality and reduce their exposure to common contaminants, perhaps while waiting for more permanent improvements and upgrades. Household bleach is a simple, low-cost way of lowering levels of bacteria in roadside spring water that is being used as drinking water. Two drops of unscented, household bleach in one gallon of spring water successfully kills total coliform and E. coli bacteria and provides an enough leftover chlorine to continue to disinfect the water for 1-month. This information was given to spring users in southern West Virginia and southwestern Virginia and, while most people who provided feedback found the information useful, only 60% of surveyed spring users report that they plan to implement this protocol. Point-of-use faucet filters have been found to successfully reduce metals contaminant levels in drinking water in homes that use municipal water. However, few studies have tested the effectiveness of POU faucet-mounted filters in lowering contaminant levels in water in homes reliant on private wells. Faucet-mounted POU filters given to homes reliant on private wells in Virginia and southern West Virginia lowered levels of many contaminants of interest in tap water, including lead, copper, iron, and total coliform bacteria. However, in some of the filtered samples, levels of many of these contaminants were higher than at least one Safe Drinking Water Act regulation. Less than half of study participants reported that they liked using the filters with several stating that they had issues with low flowrate. Faucet-mounted POU filters can also be a useful tool in better understanding exposure to contaminants at the tap. The acid flow-through method of metals recovery has previously proven to be successful in recovering lead, and other metals, that are collected inside the filters during water treatment. In this study, an extraction method using acid was tested on filters that treated water with high or low levels of lead, iron, or copper. The filters were successful in removing lead and copper from test water, but filters were not as consistently successful in removing iron from test water. The extraction method using acid provided some recovery from filters dosed with high and low concentrations of lead (38.9-70.4%). However, recovery of copper and iron was more inconsistent, suggesting that a different method of metals recovery may be necessary. While POU treatment can be useful in improving drinking water quality in rural households, there are limits to how useful it is in certain situations, such as when treating water with extreme water quality. In order to make sure rural households have access to safe drinking water, these limits need to be addressed and efforts need to be made to figure out a way to protect and supply drinking water in a more permanent way.

No description available.

No description available.

Point-of-use (POU) drinking water treatment is a common method of providing drinking water in disaster relief situations when critical water infrastructure is damaged. In these cases, POU treatment devices can be used to treat local water until relief organizations set up more permanent water provision methods. One such POU technology is PŪR® Purifier of Water, a combined coagulation/flocculation and disinfection chemical treatment sachet produced by Procter & Gamble. PŪR® has been shown to treat contaminated water to meet water quality standards and guidelines set by the U.S. EPA for water purifiers and by the World Health Organization and The Sphere Project for emergency relief. However, the standard two-bucket method of use for PŪR® has two primary drawbacks: (1) the need for appurtenances that may not be readily available in disaster relief situations and (2) lack of a means to protect treated water from re-contamination post-treatment. An alternative to the two-bucket method is a waterbag system under development at the California Polytechnic State University, San Luis Obispo. The waterbag is a ten-liter plastic bladder with integrated filter that incorporates an all-in-one approach to drinking water treatment during emergencies. In previous studies, the first version of the waterbag consistently met World Health Organization and The Sphere Project emergency drinking water guidelines, but did not meet the pathogen reduction requirements of the U.S. EPA Guide Standard and Protocol for Testing Microbiological Water Purifiers. A second (Mark II) version, with internal mixing baffles and a microfilter, was developed to overcome the inability of the first design to meet the U.S. EPA guidelines. The main purposes of the research presented herein were to (1) optimize the method of use and baffle configuration for the improved Mark II version of the waterbag, (2) determine ability of the waterbag to treat test waters with challenging initial water quality conditions, and (3) test the ability of the Mark II design and optimized method to meet the U.S. EPA Guide Standard and Protocol for Testing Microbiological Water Purifiers. For the first and second objectives, the main metric of treatment performance was the extent of flocculation, which was characterized by the turbidity of waterbag supernatant after 30 minutes of settling. The waterbag procedure was varied in several ways. The variables tested were mixing duration, mixing motion type, and the effect of a mixing delay. Several waterbag baffle designs were tested to determine the physical configuration of the waterbag which resulted in best turbulence during mixing. In addition, experiments were performed to test the ability of the Mark II waterbag to treat waters with various initial qualities, such as high organic carbon content and elevated E. coli concentrations. The results of these experiments helped to prepare for a final test in meeting the pathogen removal requirements of the U.S. EPA Guide Standard and Protocol for Testing Microbiological Water Purifiers. The procedure determined to be optimal for the Mark II waterbag treatment included five minutes of mixing using rapid 180° twisting motions at a moderate frequency of seventy 180°-twists per minute. The optimal baffle design was a 12.7 cm-wide internal mixing baffle with two cut circular holes for the promotion of turbulence during mixing. The desired post-treatment chlorine residual was achieved for different durations depending on initial organic carbon concentration. Optimal PŪR® dose to provide pathogen removals required by the U.S. EPA in the presence of Challenge Water conditions was two sachets per 10 L of water to be treated. The optimization of these design and operational procedures led to the ability of the Mark II waterbag to meet the pathogen, turbidity, pH, and non-microbiological constituent removals required by the U.S. EPA, The Sphere Project, and World Health Organization for emergency relief.

Background: Diarrhea is the passage of 3 or more loose or liquid stools per day. Globally, it is the second-leading cause of death among under-five children, accounting for 9% of all under-five deaths, and kills more young children than Acquired Immunodeficiency Syndrome (AIDS), malaria and measles combined. In developing countries, an estimated 1.8 million people die annually due to diarrheal diseases, and more than 80% of them are children under 5 years, while 88% of these deaths are in South Asia and Sub-Saharan Africa (SSA). There are limited studies that investigate the prevalence and factors associated with diarrhea in SSA despite the health burden. Method: The Demographic and Health Survey (DHS) children’s recode dataset of 2015 for Chad was used for this study. The predictor variables were; age of child, source of drinking water, maternal highest level of education, drank from bottle with nipple, and the outcome variable was diarrhea recently. Descriptive statistics for all variables were completed, and Chi-square analyses were conducted to determine associations between predictor variables and the outcome, diarrhea recently. Simple and multiple logistic regressions were completed to determine factors that predict diarrhea in the last two weeks. Odds ratios, 95% confidence intervals, and p-values were reported. Results: The total sample size was (N=16,710). About 3292 (19.70%) children had diarrhea, 13418 (80.30%) children had no diarrhea. A high prevalence of diarrhea in under-five children was observe particularly in those who drink water from unprotected well (1070 cases), had mothers with only primary level of education (796 cases), and did not drink from bottles with nipple (2961 cases). Based on the age of child, the odds of having diarrhea were over 60% lower in children 3 years old and below [aOR = 0.39, C.I (0.279-0.538), p <.0001] compared to 4 years old and above. Based on the source of drinking water, children that drank from a protected spring were 74% less likely to have diarrhea [0.26, 0.084-0.827, p=0.0223] compared to those that drank from other sources. The study also showed that children that drank from bottles with nipple were 16% less likely of having diarrhea [0.84, 0.726-0.968, p=0.0166] compared to those that did not drink from bottles with nipple. However, maternal highest level of education had no significant association with the odds of having diarrhea in these children. Conclusion: Caregivers should ensure absolute hygiene and provide safe drinking water to under-five children, especially those above 3 years who may easily access contaminated water sources themselves. We also encourage the use of bottles with nipple heads for drinking in children. Further studies are needed in SSA on other factors influencing diarrhea risk in those under five.

<p> Heavy metals, especially arsenic, have become a hot research topic due to their high toxicity and low removal efficiency in drinking water. Biofouling is one of the main factors affecting the removal efficiency of point-of-use (POU) water filtration systems. However, limited information is available on the effect of biofouling on heavy metal removal by POU systems. The aim of this study was to investigate how biofouling affects the removal efficiency of heavy metals,  especially arsenic, by different POU systems. Daily water use patterns in the U. S. households were simulated under laboratory conditions for the operation of POU systems. Sodium acetate was added to tap water to simulate an assimilable organic carbon source that contributes to biofouling formation and the concentration of sodium acetate gradually increased from 100 μg/L to 400 μg/L.  Sodium meta-arsenate (100 μg/L) was added to tap water to test its removal efficiency by POU  systems. Biofouling development and metal removal efficiency were monitored and correlated.  The results showed that arsenic removal efficiency and biofouling were positively correlated in both the activated carbon (AC) and reverse osmosis (RO) POU systems. Other conditions, such as temperature and flow rate, were negatively correlated with metal removal efficiencies in both systems. Overall, biofouling has been shown to contribute to improved removal efficiency of arsenic by POU, and the promotion effect was more significant in AC systems than in RO systems.  The results may contribute to an improved understanding of the maintenance of POU systems for heavy  metal removal </p>

Protecting drinking water supplies from pathogens such as Cryptosporidium parvum is a major concern for water treatment plants worldwide. The sensitivity and specificity of current detection methods are largely determined by the effectiveness of the concentration and separation methods used. In this study, disposable microfluidic micromixers were fabricated to effectively isolate Cryptosporidium parvum Oocysts from water samples, while allowing direct observation of Oocysts captured in the device using high quality immunofluorescence microscopy. In parallel, quantitative analysis of the capture yield was carried out by analyzing the waste from the microfluidics outlet with an Imaging Flow Cytometer. At the optimal flow rate, capture efficiencies higher than 95% were achieved in spiked samples, suggesting that scaled microfluidic isolation and detection of Cryptosporidium parvum will provide a faster and more efficient detection method for Cryptosporidium compared to other available laboratory-scale technologies.

Climate change and increased pressure on water resources through urban and peri-urban population growth present some major uncertainties to the sustainable provision of good quality water, sanitation and hygiene (WASH) services, particularly to small-scale decentralized systems which are considered more vulnerable compared to centralized systems. The concept of “resilience” could be useful when dealing with such uncertainties. It deals with planning for shocks and stressors which could help address long-term water security and sanitation challenges. The aim of this research is to explore the relevance of the concept of resilience in dealing with uncertainties for decentralized WASH systems. Through literature review, interviews (n=22) and group discussions (n=18), the relevance of the 7 resilience principles, developed by SRC, to WASH planning for decentralized systems was explored. WHO community water and sanitation planning guidelines were reviewed to determine how resilience could add useful aspects to management of decentralised WASH systems.  Results showed that the resilience concept is important in planning and management of decentralized WASH systems, since, with the resilience principles as a basis, there is potential to involve different stakeholders to share knowledge, skills and resources across multiple scales. The three resilience principles considered most important from the 7 SRC resilience principles for decentralized WASH were identified as: 1) Broadening participation, 2) Maintenance of diversity and redundancy, and 3) Management of slow changing variables and feedbacks. Other important WASH aspects missing from the resilience principles were: 1) Contextuality, 2) Accountability, 3) Equity and human rights, 4) Monitoring and maintenance, 5) Resource capacity. Two case studies served as examples of how decentralized WASH systems are managed in a high-income country (Värmdö, Sweden) and  a low/middle income country (MSETO, Kenya). In both cases, applied resilience principles were identified together with areas of improvement. With reference to resilience, Värmdö municipality showed strength in the flow of information (connectivity) between actors but lacked integrated WASH planning guidelines and diversity of water supplies. The MSETO project exhibited strength in overlapping responsibilities (polycentric governance) but lacked management of slow changing variables and feedbacks, linked to the lack of adequate re-sources. The analysis of WHO Water Safety Plans and sanitation safety planning guidelines through the resilience framework revealed that the WHO guidelines have a heavy focus on technical aspects and lack an integrated approach involving polycentric governance and complex adaptive system thinking. There is need for the revision of the guide-lines to incorporate community social aspects, strategies of improving water availability and consideration of complex adaptive systems thinking. Municipalities and practitioners are recommended to consider resilience principles as well as the identified missing aspects in WASH planning and interventions. Further research is needed investigating necessary conditions for the application of resilience principles and important trade-offs.