Public Drinking Water Systems Research Articles

Supply system factors associated with microbiological drinking water safety in regional New South Wales, Australia, 2001–2007

To determine factors associated with microbiological safety of public drinking water systems in regional New South Wales (NSW), Australia. We analysed 107,000 end-user drinking water samples for an association between detection of Escherichia coli and drinking water system features, sample year and season using NSW Health Drinking Water Monitoring Program data, 2001-2007. We used negative binomial generalized estimating equations with adjustment for autocorrelation and clustering. We detected E. coli in over 2% of samples from 40% (129/323) of systems. E. coli detection was significantly more common in earlier years and during summer (p<0.001). On multivariate analysis E. coli detection was significantly associated with smaller systems; watercourse sources; no disinfection or disinfection with ultraviolet only; and higher post-treatment mean turbidity (all p< or =0.01). Detection was most strongly associated with lack of disinfection (incidence rate ratio 12.6, p<0.001) and smaller supply systems (1% reduction in E. coli detection for each 1,000 person increase in supply population, p=0.004). Ultraviolet disinfection alone was the least effective disinfection method (p<0.001). Even in developed countries, drinking water systems without disinfection or serving small populations appear vulnerable to the effects of faecal contamination, which presents a risk of waterborne disease outbreaks.

A review of perchlorate occurrence in public drinking water systems

The national occurrence of perchlorate in drinking water was analyzed and mapped by compiling data from existing perchlorate occurrence surveys. The existing surveys included studies conducted by utilities for the first Unregulated Contaminant Monitoring Rule and by the states of Arizona, California, Massachusetts, and Texas. Perchlorate was detected in 26 states, Puerto Rico, and the Mariana Islands and was found in at least one source of approximately 5% of the nation—s large (&gt; 10,000 population) public water systems. When found, perchlorate was typically present at concentrations of &lt; 12 μg/L. Some water utilities that detected perchlorate have discontinued the use of perchlorate‐contaminated sources. On the basis of the results of a 2007 phone survey, it is estimated that at least 50 mgd of potable water production has been taken off line as a result of perchlorate contamination.

Addition to “Response to Comment on ‘Occurrence and Potential Significance of Perfluorooctanoic Acid (PFOA) Detected in New Jersey Public Drinking Water Systems’”

Addition to “Response to Comment on ‘Occurrence and Potential Significance of Perfluorooctanoic Acid (PFOA) Detected in New Jersey Public Drinking Water Systems’”

Response to Comment on “Occurrence and Potential Significance of Perfluorooctanoic Acid (PFOA) Detected in New Jersey Public Drinking Water Systems”

Response to Comment on “Occurrence and Potential Significance of Perfluorooctanoic Acid (PFOA) Detected in New Jersey Public Drinking Water Systems”

Comment on “Occurrence and Potential Significance of Perfluorooctanoic Acid (PFOA) Detected in New Jersey Public Drinking Water Systems”

Comment on “Occurrence and Potential Significance of Perfluorooctanoic Acid (PFOA) Detected in New Jersey Public Drinking Water Systems”

Assessing Children's Exposures and Risks to Drinking Water Contaminants: A Manganese Case Study

ABSTRACT Background: Compared to adults, children maybe more highly exposed to toxic substances in drinking water because they consume more water per unit of body weight. The U.S. Environmental Protection Agency (USEPA) has developed new guidance for selecting age groups and age-specific exposure factors for assessing children's exposures and risks to environmental contaminants. Research Aim: To demonstrate the application and importance of applying age-specific drinking water intake rates, health reference values, and exposure scenarios when assessing drinking water exposures because these approaches illustrate the potential for greater potential for adverse health effects among children. Methods: manganese, an essential nutrient and neurotoxicant, was selected as a case study and chemical of potential concern for children's health. A screening-level risk assessment was performed using age-specific drinking water intake rates and manganese concentrations from U.S. public drinking water systems. Results: When age-specific drinking water intake rates are used to calculate dose, formula-fed infants receive the highest dose of manganese from drinking water compared to all other age groups. Estimated hazard quotients suggest adverse health effects are possible. Use of USEPA's standardized childhood age groups and childhood exposure factors significantly improves the understanding of childhood exposure and risks.

Groundwater quality of individual wells and small systems in Arizona

A study of the microbial, physical, and chemical quality of nondisinfected individual and small groundwater drinking water systems in Arizona was conducted. Forty‐nine groundwater sources were tested (10 small public water systems and 39 individual wells). Forty‐three percent of the systems were positive for total coliforms, 16% for fecal coliforms, and 4% for Escherichia coli. Twenty‐nine percent of the wells were positive for enterococci, and 57% for Aeromonas hydrophila. Helicobacter pylori, noroviruses, rotaviruses, adenoviruses, enteroviruses, and hepatitis A were not detected. Metals that exceeded drinking water standards included arsenic, aluminum, iron, lead, manganese, molybdenum, selenium, and uranium. Most of the metals evaluated in this study were at greater concentrations in public drinking water systems than in individual wells. In total, 95% of the well water sources exceeded at least one primary and/or secondary drinking water standard.

Occurrence and Potential Significance of Perfluorooctanoic Acid (PFOA) Detected in New Jersey Public Drinking Water Systems

After detection of perfluorooctanoic acid (PFOA) in two New Jersey (NJ) public water systems (PWS) at concentrations up to 0.19 microg/L, a study of PFOA in 23 other NJ PWS was conducted in 2006. PFOA was detected in 15 (65%) of the systems at concentrations ranging from 0.005 to 0.039 microg/L. To assess the significance of these data, the contribution of drinking water to human exposure to PFOA was evaluated, and a health-based drinking water concentration protective for lifetime exposure of 0.04 microg/L was developed through a risk assessment approach. Both the exposure assessment and the health-based drinking water concentrations are based on the previously reported 100:1 ratio between the concentration of PFOA in serum and drinking water in a community with highly contaminated drinking water. The applicability of this ratio to lower drinking water concentrations was confirmed using data on serum levels and water concentrations from other communities. The health-based concentration is based on toxicological end points identified by U.S. Environmental Protection Agency (USEPA) in its 2005 draft risk assessment Recent information on PFOA's toxicity not considered in the USEPA risk assessment urther supports the health-based concentration of 0.04 microg/L. In additional sampling of 18 PWS in 2007-2008, PFOA in most systems was below the health-based concentration. However, PFOA was detected above the health-based concentration in five systems, including one not previously sampled.

Targeting the rpoB gene using nested PCR-restriction fragment length polymorphism for identification of nontuberculous mycobacteria in hospital tap water

Nontuberculous mycobacteria (NTM) are ubiquitous in the environment and can cause nosocomial infections in immunocompromised patients. Recently the presence of NTM in public drinking water and hospital water distribution systems has been reported. Their ability to form biofilms and their resistance to chlorine both contribute to their survival and colonization in water distribution systems. Here we analyzed thirty-two hospital tap water samples that were collected from different locations in three hospitals so as to evaluate the prevalence of NTM species. The water samples were concentrated by membrane filtration and then eluted with sterilized water following sonication. Two-step direct PCR targeting the rpoB gene, restriction fragment length polymorphism (RFLP) using the MspI restriction enzyme, and sequence analysis were performed for identification of NTM to the species level. The sequences of each PCR product were analyzed using BLASTN. Seven samples (7/32, 21.9%) were positive for NTM as determined by nested-PCR. The PCR-RFLP results indicated five different patterns among the seven positive PCR samples. The water-born NTM were identified, including M. peregrinum, M. chelonae (2 cases), M. abscessus, M. gordonae (2 cases), and Mycobacterium sp. JLS. The direct two-step PCR-RFLP method targeting the rpoB gene was effective for the detection and the differentiation of NTM species from hospital tap water.

Public Preferences Toward Environmental Risks: The Case of Trihalomethanes

We present the results of an in-depth study in a small Southern Illinois town looking at the public's preferences with respect to reducing trihalomethanes (THMs) in their public drinking water system. THMs are an interesting environmental risk to study. First they are a low-level risk created as a byproduct (via chlorination) of reducing the much larger risk of bacterial contamination. Second, THMs are a weak carcinogen (with a scientific debate over how weak) with a long latency period. Third, small towns pose an interesting policy trade-off question with respect to THMs due to the sharply rising per capita cost of carbon filtration as population decreases. Further, filtration at the home or tap level is a viable alternative to public filtration. These issues are considered in the context of designing a survey to elicit maximum willingness to pay (WTP) for a reduction in THMs. The key survey design question involves how to communicate low-level risks of different magnitudes to respondents. Respondents were randomly assigned to different risk levels and statistical tests reject the hypothesis that WTP estimates are insensitive to the risk levels assigned. Our value of a statistical life estimates are quite low relative to most estimates in the literature. Our estimates should be low, however, if respondents discount due to the long latency period. After allowing for discounting using commonly used rates, our value of a statistical life estimates are well within the range commonly found in the literature for WTP to avoid current period fatal accidents.

Between Globalization and Localization: The Case of Dutch Civil Engineering in Indonesia, 1800-1950

Globalization, understood as the process of absorbing people all over the world into one global network of economic and other ties, began roughly when Europeans started exploring the world through sailing the oceans (from the fourteenth century onward). The subsequent processes of colonialism and imperialism are stages in the unfolding globalization process. Technology made this globalization possible, but also developed in connection with it. This paper discusses globalization and technology development, focusing on colonial state formation and civil engineering development in colonial Indonesia, the former Dutch East Indies. Dutch East Indies state formation took place between 1800 and 1950, and civil engineering works were dominant in the technology involved. Dutch engineers in public service constructed 67,000 kilometers of roads, 7,500 kilometers of railways, many large bridges, modern irrigation systems covering 1.4 million hectares of rice fields, several international harbors, and 140 public drinking water systems in the archipelago. With these public works, Dutch engineers constructed the material base of the colonial and postcolonial Indonesian state. This paper shows that the case of Dutch civil engineering in Indonesia contradicts the idea that globalization implies a simple processes of diffusion from the West. Dutch East Indies civil engineering development appears to be a process in which Western technology had to be adapted to local natural, social, and cultural conditions, and was shaped by a variety of Western and non-Western actors. In addition, parts of this colonial technology diffused back to the Netherlands and elsewhere in the world.

An approach for developing a national estimate of waterborne disease due to drinking water and a national estimate model application

In this paper, the US Environmental Protection Agency (EPA) presents an approach and a national estimate of drinking water related endemic acute gastrointestinal illness (AGI) that uses information from epidemiologic studies. There have been a limited number of epidemiologic studies that have measured waterborne disease occurrence in the United States. For this analysis, we assume that certain unknown incidence of AGI in each public drinking water system is due to drinking water and that a statistical distribution of the different incidence rates for the population served by each system can be estimated to inform a mean national estimate of AGI illness due to drinking water. Data from public water systems suggest that the incidence rate of AGI due to drinking water may vary by several orders of magnitude. In addition, data from epidemiologic studies show AGI incidence due to drinking water ranging from essentially none (or less than the study detection level) to a rate of 0.26 cases per person-year. Considering these two perspectives collectively, and associated uncertainties, EPA has developed an analytical approach and model for generating a national estimate of annual AGI illness due to drinking water. EPA developed a national estimate of waterborne disease to address, in part, the 1996 Safe Drinking Water Act Amendments. The national estimate uses best available science, but also recognizes gaps in the data to support some of the model assumptions and uncertainties in the estimate. Based on the model presented, EPA estimates a mean incidence of AGI attributable to drinking water of 0.06 cases per year (with a 95% credible interval of 0.02-0.12). The mean estimate represents approximately 8.5% of cases of AGI illness due to all causes among the population served by community water systems. The estimated incidence translates to 16.4 million cases/year among the same population. The estimate illustrates the potential usefulness and challenges of the approach, and provides a focus for discussions of data needs and future study designs. Areas of major uncertainty that currently limit the usefulness of the approach are discussed in the context of the estimate analysis.

The role of disease burden measures in future estimates of endemic waterborne disease

The 1996 Safe Drinking Water Act amendments require the US Environmental Protection Agency and the Centers for Disease Control and Prevention to develop a national estimate of the occurrence of waterborne infectious disease that is attributable to public drinking water systems in the United States. Much of the information for developing the national estimate will be derived from epidemiologic data, and the primary outcome of this effort will be an estimate of the number of cases of gastrointestinal illness. While quantifying the number of these cases provides some measure of waterborne disease impact, the usefulness of this measure may be limited because the full spectrum of societal impact also involves consideration of the additional effects of these diseases such as hospitalization costs and lost productivity. If decision-makers wish to compare the impact of waterborne infectious diseases to the impact of some other public health concern (e.g. to aid in resource allocation decisions), then a comparison of case numbers may prove inadequate. Case numbers alone do not provide sufficient information about the severity of different illnesses. Society may value the avoidance of a few cases of severely debilitating illness more than it values the avoidance of many cases of mild illness. In order to compare disparate public health concerns, "burden of disease" measures that incorporate indicators of disease severity, costs, or societal values may prove essential for some types of decisions. We describe epidemiologic measures of severity, quality adjusted life years (QALYs), disability adjusted life years (DALYs), willingness-to-pay, and cost-of-illness methods commonly used for burden of disease estimates, and discuss how some of these summary measures of burden might be used for waterborne disease estimates.

A review of household drinking water intervention trials and an approach to the estimation of endemic waterborne gastroenteritis in the United States

The incidence of acute gastrointestinal illness (AGI) attributable to public drinking water systems in the United States cannot be directly measured but must be estimated based on epidemiologic studies and other information. The randomized trial is one study design used to evaluate risks attributable to drinking water. In this paper, we review all published randomized trials of drinking water interventions in industrialized countries conducted among general immunocompetent populations. We then present an approach to estimating the incidence (number of cases) of AGI attributable annually to drinking water. To develop a national estimate, we integrate trial results with the estimated incidence of AGI using necessary assumptions about the estimated number of residents consuming different sources of drinking water and the relative quality of the water sources under different scenarios. Using this approach we estimate there to be 4.26-11.69 million cases of AGI annually attributable to public drinking water systems in the United States. We believe this preliminary estimate should be updated as new data become available.

Occurrence of moulds in drinking water

In order to determine the occurrence of filamentous fungi in public drinking water systems in Norway, water from 14 water supply networks from all over the country was sampled and analysed. Networks with both ground and surface water sources were included in this study. During a one-year period, 273 water samples were collected. Frequencies of fungi in samples from raw water, treated water and from home and hospital installations were determined on the basis of incubation of 100 ml membrane-filtered samples on dichloran 18% glycerol agar media. Filamentous fungi were recovered from 62% of all samples. In ground water 42.3% of the samples were positive for mould growth, while surface waters yielded 69.7% positive samples. The risk to recover moulds from surface water is three times higher compared with ground water. It is more likely to detect moulds in cold waters and showers than in hot waters. By analysing the water reaching the consumers, the results reported in present study indicate that filamentous fungi in drinking water is not negligible, and that moulds should be considered as part of the microbiological analysis parameters in drinking water.

Talking about…

Talking about…

EVALUATING THE EFFECTIVENESS OF A FIXED WELLHEAD DELINEATION: REGIONAL CASE STUDY

The 1996 Safe Drinking Water Act amendments mandated that every state must determine the hydrogeologic origin of each public drinking water system and assess the degree to which each system may be adversely affected by potential sources of contamination. Wisconsin delineated and assessed one specific class of systems, transient noncommunity drinking water wells, with the least stringent standards of all governed system types. This study evaluates the effectiveness of Wisconsin's arbitrarily fixed radius approach used in determining susceptibility to potential contamination from 1,872 transient noncommunity ground water wells. Nearly 28 percent of the wells with contaminated water did not have any recorded potential sources of contamination within the delineation radii. Additionally, regression models derived from potential contaminant inventories within the delineation radii could not accurately predict actual incidences of water contamination. Differences between observed and expected frequencies of contamination further suggest that some transient noncommunity systems should probably be delineated with larger and more sophisticated methods that would account for varying geology and contaminant susceptibility. The majority of contamination cases without recorded potential sources of contamination within the delineation radii were in a karst area. Subsequently, the arbitrarily fixed radius delineation method should not be used in areas with karst aquifers.

Arsenic Removal from Water by Moving Bed Active Filtration

Arsenic (As) in drinking water was removed by a combined co-precipitation, active filtration process. A serpentine prereactor for ferric chloride ( FeCl3 ) reagent mixing was combined with a moving bed active filter, followed by separation of waste residuals from clean water discharge. Waste effluent, using 10% of influent for transport, was retained in a clarifier for settling prior to water recycling. Process residuals passed leach tests for landfill disposal. The pilot-scale apparatus was tested at a small community, public drinking water system in Fruitland, Id. In a 49 hour test, influent groundwater averaging 40.2±1.0 μg∕L total As (n=17) was fed at 38 L∕min (10 gpm) and Fe Cl3 solution was added at an optimized Fe to As molar ratio of 133:1. Arsenic concentrations were reduced to 3.3±1.4 μg∕L (n=49) over the test period. Research observations support the hypothesis that the formation and renewal of iron oxide-coated sand in the active filter is a viable mechanism for high efficiency As removal. Fur...

Leaded-Gasoline Additives Still Contaminate Groundwater

1,2-Dibromoethane (EDB) and 1,2-dichloroethane (DCA) were components of lead-based petroleum additives used between 1920 and 1980 in the USA. They are among the most commonly detected contaminants in US public drinking water systems that rely on groundwater. Few underground storage tank (UST) sites in the US have been tested for EDB and DCA. The historical use of EDB and DCA, their fate and transport in the environment and their health effects are described. Few states require testing for EDB and DCA in groundwater at UST sites, although all require BTEX (benzene, toluene, ethylbenzene and xylenes) analysis. Unless EDB and DCA specifically appear on the target analyte list, they are not quantified or reported. In South Carolina, testing for EDB began in 2001 and testing for DCA began in 2004. In 2004, 537 UST sites in South Carolina exceeded the EDB maximum contaminant level of 0.056 micrograms/litre.

Glacial Sediment Causing Regional‐Scale Elevated Arsenic in Drinking Water

In the upper Midwest, USA, elevated arsenic concentrations in public drinking water systems are associated with the lateral extent of northwest provenance late Wisconsin-aged drift. Twelve percent of public water systems located within the footprint of this drift (212 of 1764) exceed 10 microg/L arsenic, which is the U.S. EPA's drinking water standard. Outside of the footprint, only 2.4% of public water systems (52 of 2182) exceed 10 microg/L arsenic. Both glacial drift aquifers and shallow bedrock aquifers overlain by northwest provenance late Wisconsin-aged sediment are affected by arsenic contamination. Evidence suggests that the distinct physical characteristics of northwest provenance late Wisconsin-aged drift--its fine-grained matrix and entrained organic carbon that fosters biological activity--cause the geochemical conditions necessary to mobilize arsenic via reductive mechanisms such as reductive desorption and reductive dissolution of metal oxides. This study highlights an important and often unrecognized phenomenon: high-arsenic sediment is not necessary to cause arsenic-impacted ground water--when "impacted" is now defined as >10 microg/L. This analysis also demonstrates the scientific and economic value of using existing large but imperfect statewide data sets to observe and characterize regional-scale environmental problems.