scholarly journals Free-living amoebae, Legionella and Mycobacterium in tap water supplied by a municipal drinking water utility in the USA

2009 ◽  
Vol 8 (1) ◽  
pp. 71-82 ◽  
Author(s):  
Francine Marciano-Cabral ◽  
Melissa Jamerson ◽  
Edna S. Kaneshiro
Keyword(s):  
Drinking Water ◽  
Distribution Systems ◽  
Pathogenic Bacteria ◽  
Culture Media ◽  
Tap Water ◽  
Light And Electron Microscopy ◽  
Domestic Water ◽  
Free Living ◽  
Water Utility ◽  
The Usa

Legionella and Mycobacterium can proliferate within free-living amoebae (FLA) where they are protected from disinfectants at concentrations that can kill bacteria but not protozoa. Despite effective treatment of drinking water, microbes can enter water utility distribution systems (DS) and hence the plumbing within building premises. Additionally, biofilm formation may account for the persistence of microbes in the DS. In the present study a domestic water tap in north-central United States (USA) was sampled in March and September 2007 and analysed for FLA, Legionella and Mycobacterium. Identification of organisms was determined by growth on specific culture media, light and electron microscopy, and amplification of DNA probes specific for each organism. In both the spring and fall samples, amoebae, Legionella and Mycobacterium were detected. However, Acanthamoeba was prominent in the spring sample whereas Vahlkampfia and Naegleria were the amoebae detected in the autumn. Bacterial proliferation in laboratory cultures was noticeably enhanced in the presence of amoebae and biofilms rapidly formed in mixed amoebae and bacteria cultures. It is hypothesized that temperature affected the dynamics of FLA species population structure within the DS and that pathogenic bacteria that proliferate within FLA, which are themselves opportunistic pathogens, pose dual public health risks.

scholarly journals How Perceptions of Trust, Risk, Tap Water Quality, and Salience Characterize Drinking Water Choices

Hydrology ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 49
Author(s):  
Madeline A. Grupper ◽  
Madeline E. Schreiber ◽  
Michael G. Sorice
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Risk Perceptions ◽  
Anthropogenic Impacts ◽  
Tap Water ◽  
Water Utilities ◽  
Global Changes ◽  
Water Utility ◽  
The Public ◽  
Water Behavior

Provision of safe drinking water by water utilities is challenged by disturbances to water quality that have become increasingly frequent due to global changes and anthropogenic impacts. Many water utilities are turning to adaptable and flexible strategies to allow for resilient management of drinking water supplies. The success of resilience-based management depends on, and is enabled by, positive relationships with the public. To understand how relationships between managers and communities spill over to in-home drinking water behavior, we examined the role of trust, risk perceptions, salience of drinking water, and water quality evaluations in the choice of in-home drinking water sources for a population in Roanoke Virginia. Using survey data, our study characterized patterns of in-home drinking water behavior and explored related perceptions to determine if residents’ perceptions of their water and the municipal water utility could be intuited from this behavior. We characterized drinking water behavior using a hierarchical cluster analysis and highlighted the importance of studying a range of drinking water patterns. Through analyses of variance, we found that people who drink more tap water have higher trust in their water managers, evaluate water quality more favorably, have lower risk perceptions, and pay less attention to changes in their tap water. Utility managers may gauge information about aspects of their relationships with communities by examining drinking water behavior, which can be used to inform their future interactions with the public, with the goal of increasing resilience and adaptability to external water supply threats.

scholarly journals Application of model fitting technique to enhance bacterial regrowth potential (BRP) measurement for drinking water supply monitoring

2021 ◽  
Author(s):  
Wenjin Xue ◽  
Christopher W. K. Chow ◽  
John van Leeuwen
Keyword(s):  
Drinking Water ◽  
Water Supply ◽  
Water Samples ◽  
Distribution System ◽  
Distribution Systems ◽  
Tap Water ◽  
Treatment Plant ◽  
Drinking Water Supply ◽  
Water Supply Systems ◽  
Bacterial Regrowth

Abstract The bacterial regrowth potential (BRP) method was utilised to indirectly measure the assimilable organic carbon (AOC) as an indicator for the assessment of the microbial regrowth potential in drinking water distribution systems. A model using various microbial growth parameters was developed in order to standardise the experimental interpretation for BRP measurement. This study used 82 experimental BRP data sets of water samples collected from the water treatment plant to locations (customer taps) in the distribution system. The data were used to model the BRP process (growth curve) by a data fitting procedure and to obtain a best-fitted equation. Statistical assessments and model validation for evaluating the equation obtained by fitting these 82 sets of data were conducted, and the results show average R2 values were 0.987 for treated water samples (collected at the plant prior to chlorination) and 0.983 for tap water (collected at the customer taps). The F values obtained from the F-test are all exceeded their corresponding F critical values, and the results from the t-test also showed a good outcome. These results indicate this model would be successfully applied in modelling BRP in drinking water supply systems.

scholarly journals Water quality event detection and customer complaint clustering analysis in distribution systems

2012 ◽  
Vol 12 (5) ◽  
pp. 580-587 ◽  
Author(s):  
Stephen Mounce ◽  
John Machell ◽  
Joby Boxall
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Distribution System ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Source ◽  
Water Quality Monitoring ◽  
Water Utility ◽  
Drinking Water Distribution ◽  
Historic Data

Safe, clean drinking water is a foundation of society and water quality monitoring can contribute to ensuring this. A case study application of the CANARY software to historic data from a UK drinking water distribution system is described. Sensitivity studies explored appropriate choice of algorithmic parameter settings for a baseline site, performance was evaluated with artificial events and the system then transferred to all sites. Results are presented for analysis of nine water quality sensors measuring six parameters and deployed in three connected district meter areas (DMAs), fed from a single water source (service reservoir), for a 1 year period and evaluated using comprehensive water utility records with 86% of event clusters successfully correlated to causes (spatially limited to DMA level). False negatives, defined by temporal clusters of water quality complaints in the pilot area not corresponding to detections, were only approximately 25%. It was demonstrated that the software could be configured and applied retrospectively (with potential for future near real time application) to detect various water quality event types (with a wider remit than contamination alone) for further interpretation.

scholarly journals Change in methodology for collection of drinking water intake in What We Eat in America/National Health and Nutrition Examination Survey: implications for analysis

2012 ◽  
Vol 15 (7) ◽  
pp. 1190-1195 ◽  
Author(s):  
Rhonda S Sebastian ◽  
Cecilia Wilkinson Enns ◽  
Joseph D Goldman ◽  
Alanna J Moshfegh
Keyword(s):  
Drinking Water ◽  
Water Intake ◽  
National Health ◽  
Tap Water ◽  
Lower Percentage ◽  
Nutrition Examination Survey ◽  
Cross Sectional ◽  
Health And Nutrition ◽  
The Usa ◽  
Gender Groups

AbstractObjectiveTo provide updated estimates of drinking water intake (total, tap, plain bottled) for groups aged ≥1 year in the USA and to determine whether intakes collected in 2005–2006 using the Automated Multiple-Pass Method for the 24 h recall differ from intakes collected in 2003–2004 via post-recall food-frequency type questions.DesignCross-sectional, observational study.SettingWhat We Eat in America (WWEIA), the dietary intake component of the US National Health and Nutrition Examination Survey (NHANES).SubjectsIndividuals aged ≥1 year in 2003–2004 (n 8249) and 2005–2006 (n 8437) with one complete 24 h recall.ResultsThe estimate for the percentage of individuals who reported total drinking water in 2005–2006 was significantly (P < 0·0000) smaller (76·9 %) than that for 2003–2004 (87·1 %), attributable to a lower percentage reporting tap water (54·1 % in 2005–2006 v. 67·0 % in 2003–2004; P = 0·0001). Estimates of mean tap water intake differed between the survey cycles for men aged ≥71 years.ConclusionsSurvey variables must be examined before combining or comparing data from multiple WWEIA/NHANES release cycles. For at least some age/gender groups, drinking water intake data from NHANES cycles prior to 2005–2006 should not be considered comparable to more recent data.

The interaction of silver ions and hydrogen peroxide in the inactivation of E. coli: a preliminary evaluation of a new long acting residual drinking water disinfectant

1995 ◽  
Vol 31 (5-6) ◽  
pp. 123-129 ◽  
Author(s):  
Rami Pedahzur ◽  
Ovadia Lev ◽  
Badri Fattal ◽  
Hillel I. Shuval
Keyword(s):  
Hydrogen Peroxide ◽  
Drinking Water ◽  
Distribution Systems ◽  
Residual Effect ◽  
Silver Ions ◽  
Product Formation ◽  
Preliminary Evaluation ◽  
E Coli ◽  
The Usa ◽  
K 12

The inactivation efficiencies of silver ions, hydrogen peroxide and their combination was studied as part of a performance evaluation of the combined disinfectant for drinking water applications. The major advantages of such combined disinfectant include, low toxicity of its components, long lasting residual effect and low disinfection by product formation. Specific strains of E. coli (E. coli-B (SR-9) and E. coli K-12) were used in this study as target microorganisms and the separate and combined inactivation efficiencies of silver and hydrogen peroxide were evaluated at different concentrations and exposure durations. Both, silver and hydrogen peroxide exhibited a significant inactivation performance even at concentrations that do not pose any health risk according to the EEC, WHO and the USEPA (the USEPA Maximum Contaminant Level (MCL) of silver is 90 ppb, and currently, there is no MCL for hydrogen peroxide but it is approved as a food additive in the USA). Combinations of 1:1000 silver:hydrogen peroxide (w) exhibited higher inactivation performance as compared with each of the disinfectants alone and in some cases a synergistic effect was observed, i.e., the combined disinfectant exhibited higher inactivation performance than the sum of the inactivation levels of the separate disinfectants. Thus, for example, one hour exposure to 30 ppb silver, 30 ppm hydrogen peroxide and their combination yielded 2.87, 0.65 and 5 logs of inactivation respectively. While the rate of inactivation shown by this combined disinfectant, now available commercially in a stabilized formulation is relatively slow, it may well hold promise as a secondary disinfectant providing long lasting residuals and biofilm control required for distribution systems. Its disinfection action may be similar to chloramines, the use of which has been recently outlawed in France and in Germany and which are now under careful scrutiny in other countries due to the formation of undesirable by-products.

Culture of Helicobacter pylori from domestic water samples – the impact of strain variation on growth on solid and in liquid media

2006 ◽  
Vol 54 (3) ◽  
pp. 147-152 ◽  
Author(s):  
R.J. Owen ◽  
S.A. Chisholm ◽  
G. Brick ◽  
J.V. Lee ◽  
S. Surman-Lee ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Culture Media ◽  
Tap Water ◽  
Clinical Isolates ◽  
Strain Variation ◽  
Liquid Media ◽  
Domestic Water ◽  
Source Of Infection ◽  
Solid Media ◽  
The Impact

Helicobacter pylori is an important global human pathogen and there is growing evidence from PCR assays that contaminated drinking water might be a possible source of infection in some circumstances. There are no validated protocols for direct isolation but various culture media have been developed for possible environmental sampling. Our aim here was to investigate how inter-strain variation might affect the interpretation of results with such media. Two laboratory adapted reference strains and four recent clinical isolates were tested on four solid media and in ten liquid media. Considerable variation was found between strains in their ability to recover on the different media after stress exposure (suspension in sterile tap water). Generally, clinical isolates were less robust than the laboratory-adapted strains and, overall, the former required longer recovery times. Our findings highlighted the importance of using a range of isolates for evaluations, as examination of laboratory-adapted strains alone did not provide an accurate representation of the utility of media that may be used to recover H. pylori from water.

Pathogenic viruses in drinking-water biofilms: a public health risk?

Biofilms ◽  
2005 ◽  
Vol 2 (2) ◽  
pp. 105-117 ◽  
Author(s):  
S. Skraber ◽  
J. Schijven ◽  
C. Gantzer ◽  
A. M. de Roda Husman
Keyword(s):  
Drinking Water ◽  
Health Risk ◽  
Distribution Systems ◽  
Water Distribution ◽  
Tap Water ◽  
Field Studies ◽  
Pilot Scale ◽  
Drinking Water Distribution Systems ◽  
Virus Attachment ◽  
Pathogenic Viruses

Biofilms in drinking-water distribution systems may accumulate human pathogenic viruses. Viruses that attach to biofilm are removed from the water phase improving the water quality. However, if released in slough, it may still present a risk of infection. This review describes the available data on the presence of pathogenic viruses in drinking-water biofilms. First, biofilms of distribution systems potentially contribute to viral contamination of tap water only if infectious viruses are present initially in the water, which has been shown in several recent studies. However, only one out of three field studies showed the presence of infectious enteroviruses in natural biofilms from drinking-water networks. The presence of pathogenic viruses in biofilms points to the ability of these viruses to attach to biofilms. This has also been shown in pilot-scale studies in which bacteriophages and vaccine poliovirus strains were spiked into water and could be eluted from artificial biofilms. Reported attachment rates vary greatly and may depend on many factors such as the biofilm characteristics, the virus strain and the efficiency of viral recovery from biofilms. One study reported biphasic viral inactivation in biofilms with rapid initial inactivation followed by slow inactivation, implying that some of the attached viruses are able to remain infectious for a longer time. In several laboratory experiments, virus attachment to biofilms has been reported under various conditions; however, although detachment of sloughs in distribution systems has been observed, the presence of viruses in these sloughs was not studied. Here, we discuss the possible presence of infectious pathogenic viruses in sloughs; the extent to which these will pose a health risk remains to be investigated.

scholarly journals Control of microbial contamination in drinking water from microfiltering dispensers by dialysis ultrafilters

2016 ◽  
Vol 27 (2) ◽  
pp. 87-93 ◽  
Author(s):  
Luca Bolelli ◽  
Elida Nora Ferri ◽  
Stefano Girotti
Keyword(s):  
Drinking Water ◽  
Flow Rate ◽  
Biofilm Formation ◽  
Pathogenic Bacteria ◽  
Tap Water ◽  
Plate Count ◽  
Resistant Bacteria ◽  
Contamination Levels ◽  
Selection Of

Abstract Tap water filtering devices are widely employed to improve odor and taste of tap water, or to obtain refrigerated or sparkling drinking water. The presence of disinfectants-resistant bacteria in tap water is responsible of the biofilm formation inside tubes and tanks. The consequent contamination of dispensed water is a well-known hygiene problem because of the quite constant presence of potentially pathogenic bacteria likes P. aeruginosa. In this study, we tested the technical feasibility and effectiveness of the addition to different commercial devices of a packaged polysulphone fibers filter. We aimed to find a simple solution to implement the quality of the delivered water. Water contamination levels were determined in a wide selection of microfiltered water dispensers and we selected among them a representative group of 10 devices, new or in use. The packaged ultrafilter was introduced in about half of them, to monitor, when possible, in parallel the contamination levels and flow rate of a couple of identical units, with and without the filter. The placement of the dialysis filters resulted feasible at different positions along the water circuits of the variously designed filtration units. Delivered water resulted completely free from bacteria when the filter was placed exactly at, or very close to, the outlet in spite of the inner surfaces contamination. This performance was not obtained in presence of a more or less long tract of water circuits downstream the ultrafilter: a significant but not complete reduction of the plate count numbers was observed. The filters worked in continue over the whole study period, ten months, showing exactly the same efficiency. Moreover, the flow rate in presence of the filter was quite unaffected. The addition of this kind of filter to already in use water dispensers was technically easy, and its use can be recommended in all cases a simple but reliable water sanitization is requested.

Review / SynthèseA review of drinking-water-associated endotoxin, including potential routes of human exposure

2002 ◽  
Vol 48 (7) ◽  
pp. 567-587 ◽  
Author(s):  
William B Anderson ◽  
Robin M Slawson ◽  
Colin I Mayfield
Keyword(s):  
Drinking Water ◽  
Distribution Systems ◽  
Water Distribution ◽  
Tap Water ◽  
Disinfection Byproducts ◽  
Potential Health ◽  
Biofilm Growth ◽  
Disinfection Byproduct ◽  
Drinking Water Distribution Systems ◽  
Drinking Water Distribution

In the past decade efforts have been made to reduce the formation of harmful disinfection byproducts during the treatment and distribution of drinking water. This has been accomplished in part by the introduction of processes that involve the deliberate encouragement of indigenous biofilm growth in filters. In a controlled environment, such as a filter, these biofilms remove compounds that would otherwise be available as disinfection byproduct precursors or support uncontrolled biological activity in distribution systems. In the absence of exposure to chlorinated water, most biofilm bacteria are gram negative and have an outer layer that contains endotoxin. To date, outbreaks of waterborne endotoxin-related illness attributable to contamination of water used in hemodialysis procedures have been only infrequently documented, and occurrences linked to ingestion or through dermal abrasions could not be located. However, a less obvious conduit, that of inhalation, has been described in association with aerosolized water droplets. This review summarizes documented drinking-water-associated incidents of endotoxin exposure attributable to hemodialysis and inhalation. Typical endotoxin levels in water and conditions under which substantial quantities can enter drinking water distribution systems are identified. It would appear that endotoxin originating in tap water can be inhaled but at present there is insufficient information available to quantify potential health risks.Key words: endotoxin, lipopolysaccharide, LPS, drinking water.

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