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In the United States, most residents receive water from centralized utilities regulated under the federal Safe Drinking Water Act. Yet, a sizable portion of U.S. residents satisfy their household water needs through decentralized means, including domestic wells, very small water systems, and hauled water. These federally unregulated water users are among the most vulnerable to the impacts of climate change, particularly in aridifying regions like the Southwest. They are, however, inconsistently monitored and regulated at the Tribal, federal, state, and local levels. Compared to regulated users, very few programs exist to assist this population in securing and maintaining safe, affordable drinking water access. This neglect creates a vicious cycle whereby their water security needs remain both poorly understood and inadequately addressed. We review available data sources, regulations, assistance programs, and published studies relevant to unregulated water users across the Southwestern U.S. to illustrate this injurious feedback loop. We then propose four key areas for intervention to transform this vicious cycle into a virtuous one. Drawing on new insights from the emerging literature on modular, adaptive, and decentralized (MAD) water infrastructure, we highlight opportunities for investment and innovation to support decentralized service alongside existing investments in centralized infrastructure, and the critical need to attend to justice in the design and implementation of such policies. This article is categorized under:Science of Water > Water and Environmental ChangeHuman Water > Water GovernanceHuman Water > Rights to Water [ABSTRACT FROM AUTHOR]

The Drinking Water Tool (DWT) is a community-driven online tool that provides diverse users with information about drinking water sources and threats to drinking water quality and access due to drought. Development of the DWT was guided by the Community Water Center (CWC) as part of the Water Equity Science Shop (WESS), a research partnership integrating elements of community-based participatory research and the European Science Shop model. The WESS engages in scientific projects that inform policy change, advance water justice, and reduce cumulative exposure and disproportionate health burdens among impacted communities in California. WESS researchers conducted qualitative analysis of 15 stakeholder interviews regarding the DWT, including iterative feedback and the stakeholder consultation process as well as stakeholder perceptions of the tool's impact on California water policy, organizing, and research. Results indicate that the DWT and the stakeholder engagement process which developed it were effective in influencing policy priorities and in promoting interagency coordination at multiple levels to address water equity challenges and their disproportionate burdens, particularly among rural and low socioeconomic status areas and communities of color.

Despite the presence of millions of domestic wells in the Northeastern U.S., there is little knowledge of the vulnerability of these wells to drought. To overcome a lack of reported data on domestic well failure in the Northeastern U.S., this study evaluated whether data from well completion reports could provide insight into the number of well failures occurring during drought. In particular, the study normalizes annual domestic well completions by the number of housing starts to differentiate wells completed to replace failed wells from wells completed due to new construction (as identified from U.S. Census data at the scale of Metropolitan Statistical Areas). The correspondence of elevated normalized well completions to drought was validated by comparing to U.S. Drought Monitor metrics and the occurrence of low water levels in U.S. Geological Survey groundwater monitoring wells. The analysis was completed for 17 regions in New England and New York since the year 2000, providing 261 region-years of data. Aggregated over all region-years, normalized well completions accurately predicted the presence or absence of drought as determined by the U.S. Drought Monitor 78% of the time, and the method had a Heidke skill score of 0.337. Similar results were obtained when drought was defined by changes in water depth in USGS wells. The method suggests that in the Northeast U.S., a region experiencing drought may see domestic well failures at a rate of one in a thousand wells, as an order of magnitude estimate. [ABSTRACT FROM AUTHOR]

In many developing countries, poorly constructed pit latrines are the primary source of groundwater contamination. Approaches are needed to identify site-specific separation distances between domestic wells and pit latrines. In this study, tracer transport simulations are combined with water quality monitoring data to identify separation distances in peri-urban Dar es Salaam. Bivariate correlation and linear regression models were used to find the relationships between (1) simulated tracer and distances from the wells to the nearest pit latrines (2) simulated tracer and observed contaminants (nitrate, E. coli, and total dissolved solids). The results showed a strong correlation between tracer with nitrate and E. coli, with Pearson coefficient (r) values of 0.80 and 0.79, but a weak correlation with total dissolved solids (TDS) (r = 0.23). A strong correlation between tracer and distance for shallow and deep wells (r = −0.96, −0.76) was found. Based on the soil type and aquifer properties in the area, wells must be placed at least 34 m from a pit latrine to minimize contamination. With recent advances in sensor technologies and the availability of low-cost sensors, linking simulated tracer with observed contaminant levels may provide an alternative first approach to quickly assess human health risks associated with groundwater contamination. HIGHLIGHTS A method to determine site-specific separation distance between wells and pit latrines was developed.; Tracer transport simulations and statistical analyses were used to find relationships between tracer, distance and contaminants.; A strong correlation was found between simulated tracer, distance to the nearest pit latrine and contaminants.; In this area, wells must be placed >34 m from pit latrines to minimize contamination.;

Formal policy analysis can aid resource management where groundwater is used intensively. Approaches for developing equitable and effective pumping allocations for drought are evaluated in the context of the 2012–2016 drought in Tulare County, California, USA. Potential economic impacts of policy alternatives on two user groups with conflicting interests are considered. Tradeoffs between losses of agricultural profit and response costs for domestic wells that run dry are estimated for various maximum groundwater depth policies. A welfare maximizing approach for identifying policies that limit depth to groundwater is evaluated and found to be ineffective because agricultural opportunity costs are much larger than domestic well costs. Adding a fee for additional drought groundwater pumping is proposed as a more impactful and balanced management policy approach. For the case study presented, a fee range of $300 to $600/acre-foot ($300–$600/1,233 m3) yielded an effective groundwater management policy for reducing domestic well impacts from drought and balancing agricultural impacts of drought with the need to replenish additional drought pumping in wetter years. Recent management policies enacted in the study area agree with this finding. These results may provide a useful perspective for analytically examining and developing groundwater management policies near the study area and elsewhere. [ABSTRACT FROM AUTHOR]

Populations in peri-urban communities of Sub-Saharan Africa frequently depend on shallow aquifers and on-site sanitation facilities concurrently. Routinely, domestic wells end up too close to toilet facilities, risking groundwater contamination. For coastal communities, saltwater intrusion adds to the risk of groundwater contamination. This study assessed both risks in five peri-urban communities of Cape Coast, Ghana. Groundwater samples collected from 40 domestic wells were analyzed for physicochemical and microbial constituents. Multivariate statistics including hierarchical cluster analysis (HCA) and principal component analysis (PCA) were used to classify and link contaminants to potential sources. Results indicate high enteric bacteria contamination in 98% of the samples, as well as high enrichment in physicochemical constituents, tied largely to impacts of on-site sanitation facilities. We found that wells located within 25 m of septic tanks/toilet facilities contained higher contaminant loads than those without such facilities within 25 m of their locations. Similarly, for wells located close to point sources, the closer the water table is below the land surface (within 2 m), the higher the contaminant loads. Lastly, using molar ratios of Cl−/HCO3− and Na+/Cl− with R-mode HCA, the study isolated a few wells, located within 2 km of the coastline, that are experiencing effects of saltwater intrusion. Overall, this study provides useful information for aiding groundwater quality mitigation policy, and the baseline data for aiding future investigations in the study area. It also has broader policy implications for other peri-urban settings throughout Ghana and the entire Sub-Saharan Africa. [ABSTRACT FROM AUTHOR]

Groundwater is a critical water resource in many peri-urban areas without municipal water supply, a common situation globally, but especially in Africa. These areas contain multiple water pollution risks from various human activities, including small industry, dumping, stock and pet animals, and pit latrines. Stinkwater village, 40 km north of Pretoria in Gauteng Province, that has only partial municipal water supply, was sampled for water quality from municipal taps, boreholes and open hand-dug wells. The water quality varied greatly, with few obvious geographic or geochemical correlations, other than high bacterial counts in the open wells. The key health concerns were nitrate, fluoride and coliform bacteria (including E. coli), some at dangerous levels. Relatively subtle variations in land use, including water use and pollution sources, as well as vadose zone character, including depth to water table, permeability and recharge pathways, could account for much of the variation in water quality. The study reveals the risk of relying upon a single water quality analysis to determine groundwater conditions for an area. In areas with multiple possible pollution sources, thorough groundwater monitoring is needed to determine the usability of water resources. [ABSTRACT FROM AUTHOR]

Abstract: While the safety of public drinking water supplies in the Republic of Ireland is governed and monitored at both local and national levels, there are currently no legislative tools in place relating to private supplies. It is therefore paramount that private well owners (and users) be aware of source specifications and potential contamination risks, to ensure adequate water quality. The objective of this study was to investigate the level of awareness among private well owners in the Republic of Ireland, relating to source characterisation and groundwater contamination issues. This was undertaken through interviews with 245 private well owners. Statistical analysis indicates that respondents' source type significantly influences owner awareness, particularly regarding well construction and design parameters. Water treatment, source maintenance and regular water quality testing are considered the three primary “protective actions” (or “stewardship activities”) to consumption of contaminated groundwater and were reported as being absent in 64%, 72% and 40% of cases, respectively. Results indicate that the level of awareness exhibited by well users did not significantly affect the likelihood of their source being contaminated (source susceptibility); increased awareness on behalf of well users was associated with increased levels of protective action, particularly among borehole owners. Hence, lower levels of awareness may result in increased contraction of waterborne illnesses where contaminants have entered the well. Accordingly, focused educational strategies to increase awareness among private groundwater users are advocated in the short-term; the development and introdiction of formal legislation is recommended in the long-term, including an integrated programme of well inspections and risk assessments. [Copyright &y& Elsevier]

Problem: Groundwater contamination is a concern in rural residential subdivisions where numerous septic systems and private wells are sited in close proximity. Although most state codes regulate the construction and location of private wells, these regulations do not usually account for site-specific conditions that may impact drinking-water quality. Purpose: Groundwater models provide a technical basis for delineating groundwater flow to domestic wells. Despite their widespread use in the hydrologic sciences, planners and developers rarely have access to such models. We aimed to assess existing regulations for domestic wells and septic systems and illustrate how groundwater models can be used to evaluate strategies for additional drinking-water protection in unsewered residential subdivisions. Methods: We developed groundwater flow models for two subdivisions in southern Wisconsin, analyzed the results, and disseminated them to local officials, developers, and residents. Results and conclusions: Models of both subdivisions indicate that deeper individual wells or a single community well within a protected source area would improve the likelihood of obtaining high-quality drinking water. In response, several homeowners in one subdivision chose to pay for deeper wells and well casings or individual home water-treatment systems. The developer of the second site incorporated an unenforceable recommendation for deeper well casings into subdivision covenants, but none of the wells drilled so far have followed the recommendation. Implementing and enforcing well construction or setback criteria based on model results may require changing Wisconsin state codes to explicitly define what can and cannot be regulated at the local level. Takeaway for practice: Hydrogeologists can use standard groundwater modeling methods and information about local hydrologic conditions to inform planners as they develop guidelines to improve drinking-water quality. Partnerships between local hydrogeologists and planners are essential because differences in hydrogeologic setting, groundwater quality concerns, and regulatory structure will cause model results and proposed guidelines to vary on a case-by-case basis. Research support: Funding for this research was provided by the EPA Science to Achieve Results (STAR) graduate fellowship program, the University of Wisconsin Groundwater Resources Advisory Council (administered by the Wisconsin Water Resources Institute), and the Wisconsin Department of Natural Resources. [ABSTRACT FROM AUTHOR]

BACKGROUND: As the population and demand for safe drinking water from domestic wells increase, it is important to examine water quality and contaminant occurrence. A national assessment in 2006 by the U.S. Geological Survey reported findings for 55 volatile organic compounds (VOCs) based on 2,401 domestic wells sampled during 1985-2002. OBJECTIVES: We examined the occurrence of individual and multiple VOCs and assessed the potential human-health relevance of VOC concentrations. We also identified hydrogeologic and anthropogenic variables that influence the probability of VOC occurrence. METHODS: The domestic well samples were collected at the wellhead before treatment of water and analyzed for 55 VOCs. Results were used to examine VOC occurrence and identify associations of multiple explanatory variables using logistic regression analyses. We used a screening-level assessment to compare VOC concentrations to U.S. Environmental Protection Agency maximum contaminant levels (MCLs) and health-based screening levels. RESULTS: We detected VOCs in 65% of the samples; about one-half of these samples contained VOC mixtures. Frequently detected VOCs included chloroform, toluene, 1,2,4-trimethylbenzene, and perchloroethene. VOC concentrations generally were < 1 μg/L. One or more VOC concentrations were greater than MCLs in 1.2% of samples, including dibromochloropropane, 1,2-dichloropropane, and ethylene dibromide (fumigants); perchloroethene and trichloroethene (solvents); and 1,1-dichloroethene (organic synthesis compound). CONCLUSIONS: Drinking water supplied by domestic wells is vulnerable to low-level VOC contamination. About 1% of samples had concentrations of potential human-health concern. Identifying factors associated with VOC occurrence may aid in understanding the sources, transport, and fate of VOCs in groundwater. [ABSTRACT FROM AUTHOR]

Recent surveys of Native Americans suggest that individuals living on reservations may be at greater environmental/health risk than the population at large due to water-quality problems. Despite these surveys, no comprehensive study of environmental conditions within Native American lands as a whole has been undertaken. This study compares water-quality data from two reservations in eastern Nebraska, the Omaha and the Santee Sioux Reservations, with existing regional, state, and national datasets to determine if differences exist between reservation and non-reservation groundwater quality. An area of concern within both reservations is the high percentage of domestic wells containing coliform bacteria and exceeding the US Environmental Protection Agency (US EPA) maximum contaminant level (MCL) for nitrate-nitrogen (NO3-N). It appears that the presence of these contaminants may be linked to factors such as well construction, maintenance, and land use patterns in the immediate vicinity of the wells rather than agricultural non-point source pollution. [ABSTRACT FROM AUTHOR]

Intensive use of antibiotics promotes the occurrence and development of antibiotic resistance. Antibiotic resistance genes (ARGs) enter water environments from human and animal sources. Groundwater serves as an important water supply, while the profiles and risk of ARGs in groundwater remain unknown. The abundance and profiles of ARGs in 11 domestic wells in the Maozhou River basin of Shenzhen City were analyzed by high-throughput qPCR. The results showed that a total of 141 ARGs and 8 mobile genetic elements (MGEs) were detected, of which the genes corresponding resistance to sulfonamides, multidrugs, and aminoglycosides were the most abundant. In each well, the number of detected ARGs and MGEs ranged from 48 to 89, with an average of 68. When normalized by the abundance of 16S rRNA genes, it was found that each bacterium carried at least one ARG in the groundwater of W7, W8, and W10, while in W11, each bacterium carried at least four ARGs. Clinically relevant ARGs that code for resistance to glycopeptide ( blaSHV , blaTEM , blaCTX , and blaOXA-1 ), β -lactams ( vanB and vanC-03 ), or chloramphenicol ( floR ) were found in groundwater. In addition, the abundance of sulfonamides, multidrugs, aminoglycosides, β -lactam, and chloramphenicol resistance genes were positively correlated with the abundance of MGEs ( P <0.01), suggesting that MGEs may promote the spread of ARGs in groundwater.