Below are abstracts for published research studies from a variety of sources. Click on the article title to be taken to the complete article or to receive directions on how to purchase it.
L. Mathieu, et. al., Water Research, 55 175-184; May 15, 2014
Attempts at removal of drinking water biofilms rely on various preventive and curative strategies such as nutrient reduction in drinking water, disinfection or water flushing, which have demonstrated limited efficiency. The main reason for these failures is the cohesiveness of the biofilm driven by the physico-chemical properties of its exopolymeric matrix (EPS). Effective cleaning procedures should break up the matrix and/or change the elastic properties of bacterial biofilms. The aim of this study was to evaluate the change in the cohesive strength of two-month-old drinking water biofilms under increasing hydrodynamic shear stress T W (from ~0.2 to ~10 Pa) and shock chlorination (applied concentration at T0: 10 mg Cl 2/L; 60 min contact time). Biofilm erosion (cell loss per unit surface area) and cohesiveness (changes in the detachment shear stress and cluster volumes measured by atomic force microscopy (AFM)) were studied. When rapidly increasing the hydrodynamic constraint, biofilm removal was found to be dependent on a dual process of erosion and coalescence of the biofilm clusters. Indeed, 56% of the biofilm cells were removed with, concomitantly, a decrease in the number of the 50-300 m 3 clusters and an increase in the number of the smaller (i.e., <50 m 3) and larger (i.e., >600 m 3) ones. Moreover, AFM evidenced the strengthening of the biofilm structure along with the doubling of the number of contact points, N C , per cluster volume unit following the hydrodynamic disturbance. This suggests that the compactness of the biofilm exopolymers increases with hydrodynamic stress. Shock chlorination removed cells (-75%) from the biofilm while reducing the volume of biofilm clusters. Oxidation stress resulted in a decrease in the cohesive strength profile of the remaining drinking water biofilms linked to a reduction in the number of contact points within the biofilm network structure in particular for the largest biofilm cluster volumes (>200 m 3). Changes in the cohesive strength of drinking water biofilms subsequent to cleaning/disinfection operations call into question the effectiveness of cleaning-in-place procedures. The combined alternating use of oxidation and shear stress sequences needs to be investigated as it could be an important adjunct to improving biofilm removal/reduction procedures.
Jung AV, Le Cann P, Roig B, Thomas O, Baurès E, and Thomas MF, International Journal of Environmental Research and Public Health, 2014, 11(4), 4292-4310; (April 17, 2014).
Microbial pollution in aquatic environments is one of the crucial issues with regard to the sanitary state of water bodies used for drinking water supply, recreational activities and harvesting seafood due to a potential contamination by pathogenic bacteria, protozoa or viruses. To address this risk, microbial contamination monitoring is usually assessed by turbidity measurements performed at drinking water plants. Some recent studies have shown significant correlations of microbial contamination with the risk of endemic gastroenteresis. However the relevance of turbidimetry may be limited since the presence of colloids in water creates interferences with the nephelometric response. Thus there is a need for a more relevant, simple and fast indicator for microbial contamination detection in water, especially in the perspective of climate change with the increase of heavy rainfall events. This review focuses on the one hand on sources, fate and behavior of microorganisms in water and factors influencing pathogens’ presence, transportation and mobilization, and on the second hand, on the existing optical methods used for monitoring microbiological risks. Finally, this paper proposes new ways of research.
Ahmed W, Brandes H, Gyawali P, Sidhu JP, Toze S, Water Research, 2014 Apr 15;53:361-9.
In this study, quantitative PCR (qPCR) was used for the detection of four opportunistic bacterial pathogens in water samples collected from 72 rainwater tanks in Southeast Queensland, Australia. Tank water samples were also tested for fecal indicator bacteria (Escherichia coli and Enterococcus spp.) using culture-based methods. Among the 72 tank water samples tested, 74% and 94% samples contained E. coli and Enterococcus spp., respectively, and the numbers of E. coli and Enterococcus spp. in tank water samples ranged from 0.3 to 3.7 log₁₀ colony forming units (CFU) per 100 mL of water. In all, 29%, 15%, 13%, and 6% of tank water samples contained Aeromonas hydrophila, Staphylococcus aureus, Pseudomonas aeruginosa and Legionella pneumophila, respectively. The genomic units (GU) of opportunistic pathogens in tank water samples ranged from 1.5 to 4.6 log₁₀ GU per 100 mL of water. A significant correlation was found between E. coli and Enterococcus spp. numbers in pooled tank water samples data (Spearman's rs = 0.50; P < 0.001). In contrast, fecal indicator bacteria numbers did not correlate with the presence/absence of opportunistic pathogens tested in this study. Based on the results of this study, it would be prudent, to undertake a Quantitative Microbial Risk Assessment (QMRA) analysis of opportunistic pathogens to determine associated health risks for potable and nonpotable uses of tank water.
Larsson C, Andersson Y, Allestam G, Lindqvist A, Nenonen N, Bergstedt O, Epidemiology and Infection, 2014 Mar;142(3):592-600.
A large outbreak of norovirus (NoV) gastroenteritis caused by contaminated municipal drinking water occurred in Lilla Edet, Sweden, 2008. Epidemiological investigations performed using a questionnaire survey showed an association between consumption of municipal drinking water and illness (odds ratio 4·73, 95% confidence interval 3·53-6·32), and a strong correlation between the risk of being sick and the number of glasses of municipal water consumed. Diverse NoV strains were detected in stool samples from patients, NoV genotype I strains predominating. Although NoVs were not detected in water samples, coliphages were identified as a marker of viral contamination. About 2400 (18·5%) of the 13,000 inhabitants in Lilla Edet became ill. Costs associated with the outbreak were collected via a questionnaire survey given to organizations and municipalities involved in or affected by the outbreak. Total costs including sick leave, were estimated to be ∼8,700,000 Swedish kronor (∼€0·87 million).
Roig, B; Baures, E; Thomas, O. Water Science & Technology: Water Supply, 2014, Vol. 14 Issue 1, p1 (January 2014).
Drinking water (DW) is increasingly subject to environmental and human threats that alter the quality of the resource and potentially of the distributed water. These threats can be both biological and chemical in nature, and are often cumulated. The increase of technical frame of water quality monitoring following the evolution of water quality standards guarantee the regulation compliance in general but is not sufficient for the survey of small scale water system efficiency. The existing monitoring is not well suited to insure a good quality of distributed water, especially in the event of a sudden modification of quality. This article aims to propose alternative solutions, from the examination of monitoring practices, in a bid to limit the risk of deterioration of DW quality.
Cappello MA, et. al., Journal of Environmental Health, November 2013
In the study discussed in this article, 27 private drinking water wells located in a rural Colorado mountain community were sampled for radon contamination and compared against (a) the U.S. Environmental Protection Agency's (U.S. EPA's) proposed maximum contaminant level (MCL), (b) the U.S. EPA proposed alternate maximum contaminate level (AMCL), and (c) the average radon level measured in the local municipal drinking water system. The data from the authors' study found that 100% of the wells within the study population had radon levels in excess of the U.S. EPA MCL, 37% were in excess of the U.S. EPA AMCL, and 100% of wells had radon levels greater than that found in the local municipal drinking water system. Radon contamination in one well was found to be 715 times greater than the U.S. EPA MCL, 54 times greater than the U.S. EPA AMLC, and 36,983 times greater than that found in the local municipal drinking water system. According to the research data and the reviewed literature, the results indicate that this population has a unique and elevated contamination profile and suggest that radon-contaminated drinking water from private wells can present a significant public health concern.
Brusseau ML, Narter M, Ground Water, November 2013
Chlorinated-solvent compounds are among the most common groundwater contaminants in the United States. A majority of the many sites contaminated by chlorinated-solvent compounds are located in metropolitan areas, and most such areas have one or more chlorinated-solvent contaminated sites. Thus, contamination of groundwater by chlorinated-solvent compounds may pose a potential risk to the sustainability of potable water supplies for many metropolitan areas. The impact of chlorinated-solvent sites on metropolitan water resources was assessed for Tucson, Arizona, by comparing the aggregate volume of extracted groundwater for all pump-and-treat systems associated with contaminated sites in the region to the total regional groundwater withdrawal. The analysis revealed that the aggregate volume of groundwater withdrawn for the pump-and-treat systems operating in Tucson, all of which are located at chlorinated-solvent contaminated sites, was 20% of the total groundwater withdrawal in the city for the study period. The treated groundwater was used primarily for direct delivery to local water supply systems or for reinjection as part of the pump-and-treat system. The volume of the treated groundwater used for potable water represented approximately 13% of the total potable water supply sourced from groundwater, and approximately 6% of the total potable water supply. This case study illustrates the significant impact chlorinated-solvent contaminated sites can have on groundwater resources and regional potable water supplies.
Patterson KY, et. al., Journal of Food Composition and Analysis, August 2013
The composition of tap water contributes to dietary intake of minerals. The Nutrient Data Laboratory (NDL) of the United States Department of Agriculture (USDA) conducted a study of the mineral content of residential tap water, to generate current data for the USDA National Nutrient Database. Sodium, potassium, calcium, magnesium, iron, copper, manganese, phosphorus, and zinc content of drinking water were determined in a nationally representative sampling. The statistically designed sampling method identified 144 locations for water collection in winter and spring from home taps. Assuming a daily consumption of 1 L of tap water, only four minerals (Cu, Ca, Mg, and Na), on average, provided more than 1% of the US dietary reference intake. Significant decreases in calcium were observed with chemical water softeners, and between seasonal pickups for Mg and Ca. The variance of sodium was significantly different among regions (p < 0.05) but no differences were observed as a result of collection time, water source or treatment. Based on the weighted mixed model results, there were no significant differences in overall mineral content between municipal and well water. These results, which are a nationally representative dataset of mineral values for drinking water available from home taps, provides valuable additional information for assessment of dietary mineral intake.
Journal, American Water Works Association, March 2013
US Environmental Protection Agency data were analyzed for violations by community water systems (CWSs). Several characteristics were evaluated, including size, source water, and violation type. The data show that: (1) 55% of CWSs violated at least one regulation under the Safe Drinking Water Act that involved systems serving more than 95 million people; (2) the presence of violations was no different for groundwater and surface water systems; (3) fewer than 20% of CWSs with violations exceeded an allowable level of a contaminant in drinking water; (4) smaller water systems are no more likely than larger systems, except very large systems, to violate health-related requirements; and (5) smaller CWSs appear more likely than larger systems to violate monitoring, reporting, and notification requirements. An evaluation was also conducted of four contaminants that had health-related violations by more than 1% of CWSs: total coliform, stage 1 disinfection by-products, arsenic, and lead and copper.
American Journal of Public Health, August 16, 2012
The purpose of this study was to assess water quality in migrant farmworker camps in North Carolina and determine associations of water quality with migrant farmworker housing characteristics. Researchers collected data from 181 farmworker camps in eastern North Carolina during the 2010 agricultural season. Water samples were tested using the Total Coliform Rule (TCR) and housing characteristics were assessed using North Carolina Department of Labor standards. A total of 61 (34%) of 181 camps failed the TCR. Total coliform bacteria were found in all 61 camps, with Escherichia coli also being detected in 2. Water quality was not associated with farmworker housing characteristics or with access to registered public water supplies. Multiple official violations of water quality standards had been reported for the registered public water supplies. Conclusions: Water supplied to farmworker camps often does not comply with current standards and poses a great risk to the physical health of farmworkers and surrounding communities. Expansion of water monitoring to more camps and changes to the regulations such as testing during occupancy and stronger enforcement are needed to secure water safety.
Science of The Total Environment, August 2012
Chemical mixtures are prevalent in groundwater used for public water supply, but little is known about their potential health effects. As part of a large-scale ambient groundwater study, we evaluated chemical mixtures across multiple chemical classes, and included more chemical contaminants than in previous studies of mixtures in public-supply wells. We (1) assessed the occurrence of chemical mixtures in untreated source-water samples from public-supply wells, (2) determined the composition of the most frequently occurring mixtures, and (3) characterized the potential toxicity of mixtures using a new screening approach. The U.S. Geological Survey collected one untreated water sample from each of 383 public wells distributed across 35 states, and analyzed the samples for as many as 91 chemical contaminants. Concentrations of mixture components were compared to individual human-health benchmarks; the potential toxicity of mixtures was characterized by addition of benchmark-normalized component concentrations. Most samples (84%) contained mixtures of two or more contaminants, each at concentrations greater than one-tenth of individual benchmarks. The chemical mixtures that most frequently occurred and had the greatest potential toxicity primarily were composed of trace elements (including arsenic, strontium, or uranium), radon, or nitrate. Herbicides, disinfection by-products, and solvents were the most common organic contaminants in mixtures. The sum of benchmark-normalized concentrations was greater than 1 for 58% of samples, suggesting that there could be potential for mixtures toxicity in more than half of the public-well samples. Our findings can be used to help set priorities for groundwater monitoring and suggest future research directions for drinking-water treatment studies and for toxicity assessments of chemical mixtures in water resources.
U.S. Environmental Protection Agency, February 2012
This Handbook describes a number of steps utilities can undertake to enhance their existing planning processes to ensure that water infrastructure investments are cost-effective over their life-cycle, resource efficient, and support other relevant community goals.
Water Research Foundation, January 2012
This brief document presents the vision and roadmap and focuses on how to move forward on source water protection. The roadmap is intended to serve as a feasible, focused path toward promoting source water protection for U.S. drinking water utilities. It is not intended to serve as an official directive, but rather is a collection of observations and recommendations organized to form a path to achieving the vision.
Water Technology, August 2010
A common theme we see on a daily basis relates to drinking water infrastructure. We track news throughout the world that impacts the drinking water industry, and one of the most frequent things we see are notices from agencies and organizations about the need for communities to boil water in order to combat possible contamination. In some parts of the world, boiling water is the norm due to water supply issues. Often, these areas may be limited in their ability to develop economically, as clean water is such an integral part of daily life. It is in the developed world, however, where we have been seeing a large increase in the number of such notices.
www.nrdc.org, July 2010
Climate change will have a significant impact on the sustainability of water supplies in the coming decades. A new analysis, performed by consulting firm Tetra Tech for the Natural Resources Defense Council (NRDC), examined the effects of global warming on water supply and demand in the contiguous United States. The study found that more than 1,100 counties— one-third of all counties in the lower 48—will face higher risks of water shortages by mid-century as the result of global warming. More than 400 of these counties will face extremely high risks of water shortages.
U.S. Environmental Protection Agency, April 2007
Total coliforms have long been used in drinking water regulations as an indicator of the adequacy of water treatment and the integrity of the distribution system. Total coliforms are a group of closely related bacteria that are generally harmless. In drinking water systems, total coliforms react to treatment in a manner similar to most bacterial pathogens and many viral pathogens. Thus, the presence of total coliforms in the distribution system can indicate that the system in also vulnerable to the presence of pathogens in the system. (EPA, June 2001, page 7) Total coliforms are the indicators used in the existing Total Coliform Rule (TCR).
EPA is undertaking “a rulemaking process to initiate possible revisions to the TCR. As part of this process, EPA believes it may be appropriate to include this rulemaking in a wider effort to review and address broader issues associated with drinking water distribution systems.” (see Federal Register 68 FR 19030 and 68 FR 42907). Since the promulgation of the TCR, EPA has received stakeholder feedback suggesting modifications to the TCR to reduce the implementation burden.
The purpose of this paper is to provide information on the number and frequency of violations of the TCR and to further characterize the frequency with which different types and sizes of systems incur violations. Although EPA explores some statistical testing in this paper, the paper concentrates on presenting the data, as it is, in SDWIS/FED. Information on these frequencies will be useful in supporting several EPA initiatives, particularly the effort to review and possibly revise the TCR. This paper has been undertaken as part of the review of the TCR.
U.S. Environmental Protection Agency, 2007
There are approximately 156,000 public drinking water systems in the United States. Each of these systems regularly supplies drinking water to at least 25 people or 15 service connections. Beyond their common purpose, the 156,000 systems vary widely. The following tables group water systems into categories that show their similarities and differences. For example, the first table shows that most people in the US (286 million) get their water from a community water system. There are approximately 52,000 community water systems, but just eight percent of those systems (4,048) serve 82 percent of the people. The second table shows that more water systems have groundwater than surface water as a source--but more people drink from a surface water system. Other tables break down these national numbers by state, territory, and EPA region.
This package also contains figures on the types and locations of underground injection control wells. EPA and states regulate the placement and operation of these wells to ensure that they do not threaten underground sources of drinking water. The underground injection control program statistics are based on separate reporting from the states to EPA. The drinking water system statistics on the following pages are taken from the Safe Drinking Water Information System/Federal version (SDWIS/Fed). SDWIS/Fed is the U.S. Environmental Protection Agency's official record of public drinking water systems, their violations of state and EPA regulations, and enforcement actions taken by EPA or states as a result of those violations. EPA maintains the database using information collected and submitted by the states. Notice: Compliance statistics are based on violations reported by states to the EPA Safe Drinking Water Information System. EPA is aware of inaccuracies and underreporting of some data in this system. We are working with the states to improve the quality of the data. Read an analysis of SDWIS/Fed data quality and get more information and additional drinking water data tables
Keith N. Eshelman, Ph.D. Associate Professor, University of Maryland, Center for Environmental Studies, May 2005
A comprehensive, quantitative survey of bottled water producers in the U.S. that reveals data collected on bottled water production, specifically production from ground water, the primary source of bottled water.
Relative to other uses of ground water, bottled water production was found to be a de minimus user of ground water.
Drinking Water Research Foundation, February 2004
Bottled water is among the foods most highly regulated by FDA under the Federal Food, Drug, and Cosmetic Act (FFDCA; 21 U.S.C. -321 et seq.). Under FDA jurisdiction, bottled water is subject to extensive general food safety and labeling requirements, including prohibitions on misbranding and adulteration (21 C.F.R. --101 and 109). Also, FDA has extensive enforcement capabilities, including the power to inspect food manufacturing facilities, issue warning letters, request voluntary recalls, and issue seizure or injunction against products or companies out of compliance, including seeking criminal prosecutions. Collectively, these requirements are the cornerstone of the very safe food supply enjoyed in the United States. In addition to these general food provisions, bottled water is also required to meet federal standards applicable specifically to bottled water, including Good Manufacturing Practices (GMPs) (21 C.F.R. --110 and 129) and specific identity and quality requirements (21 C.F.R. -165.110). The GMPs for bottled water apply to every aspect of production, from source water protection, through processing, to finished water sampling.
Drinking Water Research Foundation, 1999
In February 1999, the Natural Resources Defense Council (NRDC) issued a report entitled "Bottled Water: Pure Drink or Pure Hype?" in which numerous wrong allegations against bottled water are raised. This document provides an extensive analysis and rebuttal of NRDC's conclusions, highlighting the various mistakes and wrong allegations made by NRDC.