Small Drinking Water Systems Research Articles

Small systems, big challenges: review of small drinking water system governance

Small drinking water systems (SDWS) are widely identified as presenting particular challenges for drinking water management and governance in industrialised nations because of their small customer base, geographic isolation, and limited human and financial capacity. Consequently, an increasing number and range of scholars have examined SDWS over the last 30 years. Much of this work has been technocentric in nature, focused on SDWS technologies and operations, with limited attention to how these systems are managed, governed, and situated within broader social and political–economic contexts. This review seeks to provide a comprehensive overview of the governance dimensions of SDWS by drawing together existing literature relating to SDWS governance and exploring its key themes, research foci, and emerging directions. This overview is intended to provide guidance to scholars and practitioners interested in specific aspects of SDWS governance and a baseline against which researchers can position future work. The review identified 117 academic articles published in English-language journals between 1990 and 2016 that referred to some aspect of drinking water governance in small, rural, and Indigenous communities in industrialised nations. The articles’ content and bibliographic information were analysed to identify the locations, methods, journals, and themes included in research on SDWS governance. Further analysis of SDWS’ governance dimensions is organised around four questions identified as central to SDWS research: what governance challenges are experienced by SDWS, and what are their causes, solutions, and effects? Overall, the review revealed that the SDWS governance literature is piecemeal and fragmented, with few attempts to theorise SDWS governance or to engage in interdisciplinary, cross-jurisdictional conversations. The majority of articles examine North American SDWS, retain a technocratic orientation to drinking water governance, and are published in technical or industry journals. Such research tends to focus on the governance challenges SDWS face and proposed solutions to systems’ performance, capacity, and regulatory challenges. A small but growing number of studies examine the causal factors underpinning these governance challenges and their socio-spatially differentiated impacts on communities. Looking forward, the review argues for a more holistic, integrative approach to research on SDWS governance, building on a water governance framework.

Life cycle environmental and economic implications of small drinking water system upgrades to reduce disinfection byproducts

Many of the small drinking water systems in the US that utilize simple filtration and chlorine disinfection or chlorine disinfection alone are facing disinfection byproduct (DBP) noncompliance issues, which need immediate upgrades. In this study, four potential upgrade scenarios, namely the GAC, ozone, UV30, and UV186 scenarios, were designed for a typical small drinking water systems and compared in terms of embodied energy, carbon footprint, and life cycle cost. These scenarios are designed to either reduce the amount of DBP precursors using granular activated carbon filtration (the GAC scenario) or ozonation (the ozone scenario), or replace the chlorine disinfection with the UV disinfection at different intensities followed by chloramination (the UV30 and UV186 scenarios). The UV30 scenario was found to have the lowest embodied energy (417 GJ/year) and life cycle cost ($0.25 million US dollars), while the GAC scenario has the lowest carbon footprint (21 Mg CO2e/year). The UV186 scenario consistently presents the highest environmental and economic impacts. The major contributors of the economic and environmental impacts of individual scenarios also differ. Energy and/or material consumptions during the operation phase dominate the environmental impacts of the four scenarios, while the infrastructure investments have a noticeable contribution to the economic costs. The results are sensitive to changes in water quality. An increase of raw water quality, i.e., an increase in organic precursor content, could potentially result in the ozone scenario being the least energy intensive scenario, while a decrease of water quality could greatly reduce the overall competitiveness of the GAC scenario.

Profiling chlorine residuals using DPD and amperometric field test kits in a chlorinated small drinking water system with ammonia present in source water

Effective chlorine residual monitoring of water treatment systems that have ammonia in the raw source water is crucial to ensure adequate disinfection. Understanding the limitations related to monitoring chlorine in these systems is important to help reduce risk from microbiological hazards. The presence of ammonia and the resulting chlorine demand can be very challenging to address in drinking water treatment, especially for small water systems. This study profiles a number of situations where erratic chlorine dosing, operational, and testing conditions create a false-positive free available chlorine result. This study identified that the field test kit using amperometric testing methodology is superior to the traditional DPD (N,N-diethyl-p-phenylene-diamine) tests in a water system that has the presence of ammonia with erratic chlorine dosage.

Towards a Sustainable Small Non-Community Drinking Water System in Ontario: Owners’ Risk Awareness and Perceptions to Water Safety

In Ontario, small non-community drinking water systems are defined as systems that make drinking water available to the public and are not connected to a community drinking water system. This study, using qualitative research approach, examines the risk awareness and perceptions of small non-community drinking water system owners in providing safe drinking water to their clients and protecting their water source. Our study yields the need for developing a sustainable operation model for small non-community drinking water systems. The study results provide recommendations to the regulatory agency for effective and efficient administration of the program such as offering customized and affordable training opportunities and developing effective communication strategies for owners and operators.

Life Cycle Environmental Impacts of Disinfection Technologies Used in Small Drinking Water Systems.

Treatment included cartridge filtration followed by either chlorine disinfection or ultraviolet disinfection with chlorine residual addition. Environmental performance was evaluated for various chlorine contact zone materials (plastic, concrete, steel), ultraviolet validation factors (1.2 to 4.4), and electricity sources (renewable; U.S. average, high, and low impact grids). Performance was also evaluated when filtration and chlorine residual were not required. From a life cycle assessment perspective, replacing chlorine with UV was preferred only in a limited number of cases (i.e., high pumping pressure but filtration is not required). In all others, chlorine was environmentally preferred, although some contact zone materials and energy sources had an impact on the comparison. Utilities can use these data to inform their disinfection technology selection and operation to minimize environmental and human health impacts.

Models for estimation of the presence of non-regulated disinfection by-products in small drinking water systems.

Among all the organic disinfection by-products (DBPs), only trihalomethanes (THMs) and haloacetic acids (HAAs) are regulated in drinking water, while most DBPs are not. Very little information exists on the occurrence of non-regulated DBPs, particularly in small water systems (SWS). Paradoxically, SWS are more vulnerable to DBPs because of a low capacity to implement adequate treatment technologies to remove DBP precursors. Since DBP analyses are expensive, usually SWS have difficulties to implement a rigorous characterization of these contaminants. The purpose of this study was to estimate non-regulated DBP levels in SWS from easy measurements of relevant parameters regularly monitored. Since no information on non-regulated DBPs in SWS was available, a sampling program was carried out in 25 SWS in two provinces of Canada. Five DBP families were investigated: THMs, HAAs, haloacetonitriles (HANs), halonitromethanes (HNMs), and haloketones (HKs). Multivariate linear mixed regression models were developed to estimate HAN, HK, and HNM levels from water quality characteristics in the water treatment plant, concentrations of regulated DBPs, and residual disinfectant levels. The models obtained have a good explanatory capacity since R 2 varies from 0.77 to 0.91 according to compounds and conditions for application (season and type of treatment). Model validation with an independent database suggested their ability for generalization in similar SWS in North America.

Small drinking water systems under spatiotemporal water quality variability: a risk-based performance benchmarking framework.

Traditional approaches for benchmarking drinking water systems are binary, based solely on the compliance and/or non-compliance of one or more water quality performance indicators against defined regulatory guidelines/standards. The consequence of water quality failure is dependent on location within a water supply system as well as time of the year (i.e., season) with varying levels of water consumption. Conventional approaches used for water quality comparison purposes fail to incorporate spatiotemporal variability and degrees of compliance and/or non-compliance. This can lead to misleading or inaccurate performance assessment data used in the performance benchmarking process. In this research, a hierarchical risk-based water quality performance benchmarking framework is proposed to evaluate small drinking water systems (SDWSs) through cross-comparison amongst similar systems. The proposed framework (R WQI framework) is designed to quantify consequence associated with seasonal and location-specific water quality issues in a given drinking water supply system to facilitate more efficient decision-making for SDWSs striving for continuous performance improvement. Fuzzy rule-based modelling is used to address imprecision associated with measuring performance based on singular water quality guidelines/standards and the uncertainties present in SDWS operations and monitoring. This proposed R WQI framework has been demonstrated using data collected from 16 SDWSs in Newfoundland and Labrador and Quebec, Canada, and compared to the Canadian Council of Ministers of the Environment WQI, a traditional, guidelines/standard-based approach. The study found that the R WQI framework provides an in-depth state of water quality and benchmarks SDWSs more rationally based on the frequency of occurrence and consequence of failure events.

Drinking Water Management and Governance in Canada: An Innovative Plan-Do-Check-Act (PDCA) Framework for a Safe Drinking Water Supply.

Drinking water management in Canada is complex, with a decentralized, three-tiered governance structure responsible for safe drinking water throughout the country. The current approach has been described as fragmented, leading to governance gaps, duplication of efforts, and an absence of accountability and enforcement. Although there have been no major waterborne disease outbreaks in Canada since 2001, a lack of performance improvement, especially in small drinking water systems, is evident. The World Health Organization water safety plan approach for drinking water management represents an alternative preventative management framework to the current conventional, reactive drinking water management strategies. This approach has seen successful implementation throughout the world and has the potential to address many of the issues with drinking water management in Canada. This paper presents a review and strengths-weaknesses-opportunities-threats analysis of drinking water management and governance in Canada at the federal, provincial/territorial, and municipal levels. Based on this analysis, a modified water safety plan (defined as the plan-do-check-act (PDCA)-WSP framework) is proposed, established from water safety plan recommendations and the principles of PDCA for continuous performance improvement. This proposed framework is designed to strengthen current drinking water management in Canada and is designed to fit within and incorporate the existing governance structure.

Decision-making scheme for disinfection by-product monitoring intended for small drinking water systems

Trihalomethanes (THMs) and haloacetic acids (HAAs) are the most prevalent disinfection by-products (DBPs) in drinking water and their occurrence is regulated in several countries.

Exploring the relationships between small non-community drinking water system characteristics and water system performance in Ontario, Canada.

The objectives of this work were to investigate the relationships between characteristics of small non-community drinking water systems (SDWSs) and the performance of these systems with respect to Escherichia coli testing and risk ratings. Ontario-wide SDWS data were analysed using regression models with outcomes of (1) having an adverse E. coli test result in the 12 months prior to the last inspection and (2) the SDWS risk rating (high/medium vs. low risk) that is assigned by public health inspectors. Almost 34% (2,364/7,003) of SDWSs did not utilize treatment, more commonly for ground water than surface supplies (P < 0.001). The odds of having a positive E. coli test result were greater in systems using ground water with treatment (OR = 2.00; 95% CI 1.23-3.24) and surface water with treatment (OR = 1.97; 95% CI 1.05-3.71) compared to ground water with no treatment. The odds of having a water system rated high or medium compared to low risk was greater if the water system operated seasonally (OR = 1.36; 95% CI 1.17-1.59), had an adverse E. coli test result (OR = 1.66; 95% CI 1.09-2.53), and in specific facility types. This research helps to inform existing training opportunities available to SDWS operators in Ontario, and to better standardize the SDWS risk assessment process.

Framework for continuous performance improvement in small drinking water systems

Continuous performance improvement (CPI) can be a useful approach to overcome water quality problems impacting small communities. Small drinking water systems (SDWSs) struggle to meet regulatory requirements and often lack the economic and human resource flexibility for immediate improvement. A CPI framework is developed to provide SDWS managers and operators an approach to gauge their current performance against similar systems and to track performance improvement from the implementation of the new technologies or innovations into the future. The proposed CPI framework incorporates the use of a water quality index (WQI) and functional performance benchmarking to evaluate and compare drinking water quality performance of an individual water utility against that of a representative benchmark. The results are then used to identify and prioritize the most vulnerable water quality indicators and subsequently identify and prioritize performance improvement strategies. The proposed CPI framework has been demonstrated using data collected from SDWSs in the province of Newfoundland and Labrador (NL), Canada and using the Canadian Council of Ministers of the Environment (CCME) WQI.

Water Quality in Selected Small Drinking Water Systems of Missouri Rural Communities

Small drinking water treatment systems (serving &lt;10,000 population) in rural communities frequently encounter multiple challenges in water quality and federal regulatory compliance, especially the disinfection byproduct (DBP) regulations, due to source water variations, limited resources, and aging infrastructures. Unlike most studies on the DBP control using synthetic water in laboratory settings, this research aimed to identify the major water quality issues confronting small systems in the state of Missouri (MO), the United States of America (USA). Three small systems were selected based on source water and geographic locations. Water samples were collected quarterly from each major treatment process during the period of May 2012 to March 2013 and analyzed to identify the treatment effectiveness and potential water quality issues in each small system. Results of water quality characterization showed that the major water quality issue in the selected small systems was the low efficiency of dissolved organic carbon (DOC) removal, especially the DOC species that are considered as the DBP precursors. Most collected water samples had a higher trihalomethane formation potential (THMFP) than the United States Environmental Protection Agency (USEPA) maximum contaminant limit (MCL) (80 μg/L). Based on the analysis of the treatment efficiency in each system, several strategies for water quality improvement were recommended, and a few of which have been implemented in the small systems, leading to improved drinking water quality and compliance with the USEPA DBP regulations. This study would provide a valuable aid to small system operators and local water authority in context of water quality improvement and the regulatory compliance.

A Systematic Review of Waterborne Disease Outbreaks Associated with Small Non-Community Drinking Water Systems in Canada and the United States.

BackgroundReports of outbreaks in Canada and the United States (U.S.) indicate that approximately 50% of all waterborne diseases occur in small non-community drinking water systems (SDWSs). Summarizing these investigations to identify the factors and conditions contributing to outbreaks is needed in order to help prevent future outbreaks.ObjectivesThe objectives of this study were to: 1) identify published reports of waterborne disease outbreaks involving SDWSs in Canada and the U.S. since 1970; 2) summarize reported factors contributing to outbreaks, including water system characteristics and events surrounding the outbreaks; and 3) identify terminology used to describe SDWSs in outbreak reports.MethodsThree electronic databases and grey literature sources were searched for outbreak reports involving SDWSs throughout Canada and the U.S. from 1970 to 2014. Two reviewers independently screened and extracted data related to water system characteristics and outbreak events. The data were analyzed descriptively with ‘outbreak’ as the unit of analysis.ResultsFrom a total of 1,995 citations, we identified 50 relevant articles reporting 293 unique outbreaks. Failure of an existing water treatment system (22.7%) and lack of water treatment (20.2%) were the leading causes of waterborne outbreaks in SDWSs. A seasonal trend was observed with 51% of outbreaks occurring in summer months (p<0.001). There was large variation in terminology used to describe SDWSs, and a large number of variables were not reported, including water source and whether water treatment was used (missing in 31% and 66% of reports, respectively).ConclusionsMore consistent reporting and descriptions of SDWSs in future outbreak reports are needed to understand the epidemiology of these outbreaks and to inform the development of targeted interventions for SDWSs. Additional monitoring of water systems that are used on a seasonal or infrequent basis would be worthwhile to inform future protection efforts.

Using Data Mining to Understand Drinking Water Advisories in Small Water Systems: a Case Study of Ontario First Nations Drinking Water Supplies

Although access to safe drinking water is widely assumed to be universal, small drinking water systems in many countries continue to experience an unacceptably large number of drinking water advisories (DWAs). The goal of this research is to describe novel data mining tools that identify the factors contributing to DWAs in small drinking water systems. A dataset containing information related to First Nations drinking water systems in the Province of Ontario, Canada is used for the case study. A decision tree classifier (one of the fastest and most versatile predictive modeling algorithms currently available for data mining) visually maps out the relationship of system characteristics (e.g., source water, system age, and operator certification) to DWA likelihood. The developed model achieves an overall accuracy of 71 % during repeated cross-validation of predictive performance and is of utility when prioritizing future expenditures aimed at proactively reducing the risk of delivering compromised water.

Short-term spatial and temporal variability of disinfection by-product occurrence in small drinking water systems

Disinfection by-products (DBPs) constitute a large family of compounds. Trihalomethanes and haloacetic acids are regulated in various countries, but most DBPs are not. Monitoring DBPs can be delicate, especially for small systems, because various factors influence their formation and speciation. Short-term variations of DBPs can be important and particularly difficult for small systems to handle because they require robust treatment and operation processes. According to our knowledge, for the first time, our study covers the short-term variability of regulated and non-regulated DBP occurrence in small systems in the summer. An intensive sampling program was carried out in six small systems in Canada. Systems in the provinces of Newfoundland and Labrador and Quebec were sampled daily at the water treatment plant and at six different locations along the distribution system. Five DBP families were studied: trihalomethanes, haloacetic acids, haloacetonitriles, halonitromethanes and haloketones. Results show that there were considerable variations in DBP levels from week to week during the month of study and even from day to day within the week. On a daily basis, DBP levels can fluctuate by 22% to 96%. Likewise, the large number of sampling locations served to observe DBP variations along the distribution system. Observations revealed some degradation and decomposition of non-regulated DBPs never before studied in small systems that are associated with the difficulty these systems experience in maintaining adequate levels of residual disinfectant. Finally, this study reveals that the short term temporal variability of DBPs is also influenced by spatial location along the distribution system. In the short term, DBP levels can fluctuate by 23% at the beginning of the system, compared to 40% at the end. Thus, spatial and temporal variations of DBPs in the short term may make it difficult to select representative locations and periods for DBP monitoring purposes in small systems.

Cryptosporidium in small water systems in Puerto Rico: a pilot study.

A pilot study was undertaken to investigate the occurrence of Cryptosporidium in four very small drinking water systems supplying communities in rural Puerto Rico. Water samples (40 L) were collected and oocysts were concentrated by calcium carbonate flocculation, recovered by immunomagnetic separation and detected by immunofluorescence microscopy. Cryptosporidium oocysts were identified in all four systems. This is the first report of evidence of the potential public health risk from this chlorine-resistant pathogen in Puerto Rican small water systems. Further work is warranted to fully assess the health risks that Cryptosporidium and other protozoa pose to populations served by community-managed small drinking water systems.

Treatment, residual chlorine and season as factors affecting variability of trihalomethanes in small drinking water systems

Seasonal variability in source water can lead to challenges for drinking water providers related to operational optimization and process control in treatment facilities. The objective of this study is to investigate seasonal variability of water quality in municipal small water systems (<3000 residents) supplied by surface waters. Residual chlorine and trihalomethanes (THM) were measured over seven years (2003–2009). Comparisons are made within each system over time, as well as between systems according to the type of their treatment technologies. THM concentrations are generally higher in the summer and autumn. The seasonal variability was generally more pronounced in systems using chlorination plus additional treatment. Chloroform, total THM (TTHM) and residual chlorine concentrations were generally lower in systems using chlorination plus additional treatment. Conversely, brominated THM concentrations were higher in systems using additional treatment. Residual chlorine was highest in the winter and lowest in the spring and summer. Seasonal variations were most pronounced for residual chlorine in systems with additional treatment. There was generally poor correlation between THM concentrations and concentrations of residual chlorine. Further study with these data will be beneficial in finding determinants and indicators for both quantity and variability of disinfection byproducts and other water quality parameters.

The costs of small drinking water systems removing arsenic from groundwater

The US Environmental Protection Agency (EPA) conducted an Arsenic Demonstration Program whereby the Agency purchased, installed, and evaluated the performance and cost of 50 small water arsenic removal treatment systems in the USA. A major goal of the program was to collect high-quality cost data (capital and operational and maintenance (O&M)) from the long-term operation (1–4 years) of these systems. The technologies consisted of adsorptive media (AM), iron removal (IR), coagulation/filtration (C/F), ion exchange (IX), reverse osmosis, and point-of-use devices, which reduced the arsenic to less than the EPA maximum contaminant level of 10 μg/L. This paper presents the capital and O&M cost of 48 treatment systems ranging in size from 10 to 770 gal/min (gpm) (38–2,915 L/min). The capital cost of the systems ranged from $477 to $6,171 per gpm ($126–$1,632 per L/min) of design flow and the O&M cost from $0.07 to $22.88 per 1,000 gal ($0.02–$6.05 per 1,000 L) of treated water. AM had a lower capital, but a higher O&M cost than IR, C/F, and IX. The media replacement cost for the AM systems averaged 80% of the O&M cost and was the main cause of the higher O&M cost of the AM systems.

Occurrence of regulated and non-regulated disinfection by-products in small drinking water systems

The occurrence of regulated and non-regulated disinfection by-products (DBPs) was investigated in the drinking water of small systems in two provinces in Canada, Newfoundland and Labrador (NL) and Quebec (QC), through an intensive sampling program. Sixteen DBPs were studied: four trihalomethanes (THMs), five haloacetic acids (HAAs), four haloacetonitriles (HANs), one halonitromethane, chloropikrin (CPK) and two haloketones (HKs). Average measured concentrations of these compounds were much higher than those reported in the literature for medium and large systems. The measured average value for THMs was 75μgL−1 (Stdv=69μgL−1); HAAs, 77μgL−1 (Stdv=75μgL−1); HANs, 2.5μgL−1 (Stdv=1.8μgL−1); CPK, 0.4μgL−1 (Stdv=0.3μgL−1) and HKs, 6.0μgL−1 (Stdv=4.5μgL−1). The gap (some 10 times difference) between the average levels of regulated DBPs (THMs, HAAs) and non-regulated DBPs (HANs, CPK and HKs) is comparable to that observed in large systems where the occurrence of the same compounds has been reported. Generally, investigated DBPs followed a comparable seasonal evolution during the year: they decreased between the fall and winter and then increased to eventually reach a maximum in late summer. This trend was less observable in NL than in QC. However, observed seasonal fluctuations of DBPs were less considerable than those observed in medium and large systems located in similar temperate environments reported in the literature. Spatial variations from the plant to the extremities were high and comparable to those observed in large systems, which is surprising, considering the smaller size of distribution networks supplying small communities. Generally speaking, the results support the premise that problems associated with implementing treatment that removes DBP precursors in water submitted to chlorination can increase population exposure to these contaminants in small systems.

Implementing Treatment Sequences to Promote Reduction of DBPs in Small Drinking Water Systems

The performance of three drinking water treatment sequences found in small community systems in reducing disinfection by-product precursor concentrations and the corresponding disinfection by-product formation potential was evaluated. Raw water quality and its potential for effective removal were characterized by the specific ultraviolet absorbance (SUVA) components of absorbance of ultraviolet light at 254 nm wavelength (UV254) and dissolved organic carbon (DOC). The results demonstrate that, for the source water qualities tested (hydrophobic SUVA with moderate DOC content, 2.0 to 4.8 L/(mg.m) and 4.1 to 6.3 mg DOC/L), there was a tendency to produce a higher percentage of total trihalomethane (TTHM) over the five regulated species of haloacetic acid (HAA5). The treatment sequence and chemical selection play a critical role in the ability of a small community system operator to achieve compliance with the concentration of regulated disinfection by-products. For the waters tested ferric chloride coagulants perform better at reducing the higher molecular weight, hydrophobic organic precursors. Powdered activated carbon does not perform as well with these source waters unless its application is followed by a clarification process that effectively forms a sludge blanket. This research provides additional criteria for linking source water quality with treatment sequence for sustainable management of disinfection by-product (DBP) compliance.