Pathogens

Author(s):  
William M. Alley ◽  
Rosemarie Alley

This chapter examines microbial contamination of groundwater that can threaten drinking water supplies and the importance of proper well construction and protection. Case studies are presented of E. coli poisoning in Walkerton, Ontario and viruses in Wisconsin. The Walkerton incident in 2000 caused Canadian provinces to take a hard look at their drinking water safety through better monitoring, enforcement, training, and source-water protection programs. The Wisconsin case study illustrates the potential for viruses from leaking sewers to contaminant municipal wells.

Author(s):  
Robert J Patrick

The protection of drinking water sources continues to gain momentum in First Nation communities on the Canadian Prairie. Through the identification of potential threats to drinking water sources communities are taking action to mitigate those threats. This article explores the extent to which climate change has been taken into consideration in recent source water protection planning community exercises. In addition, this article describes how source water protection planning has potential to enhance community adaptation strategies to reduce the impacts of climate change on source water and drinking water systems. Results are based on six case studies from Alberta and Saskatchewan.


2009 ◽  
Vol 9 (2) ◽  
pp. 127-132 ◽  
Author(s):  
Gertjan Medema ◽  
Patrick Smeets

System assessment is the part of the Water Safety Plan that evaluates whether a water supply system is capable of producing drinking water that meets the health-based targets. System assessment can be done at increasing level of detail, requiring more site specific information as the level of detail increases. Four case studies are presented with increasing level of detail, showing the type of information that is required for each of these levels and how each level informs risk management. The first case study shows how a system assessment can be performed without other site specific information than the type of source water and the type of treatment processes. The required data for the system assessment are collected from the large body of literature available. The second case study uses site specific microbial indicator data. The third study uses pathogen data and the fourth case study combines data on pathogens, microbial indicators and process parameters. The case studies show that the level of detail required largely depends on the risk management question.


2015 ◽  
Vol 51 (11) ◽  
pp. 8741-8756 ◽  
Author(s):  
Matthew T. Heberling ◽  
Christopher T. Nietch ◽  
Hale W. Thurston ◽  
Michael Elovitz ◽  
Kelly H. Birkenhauer ◽  
...  

2020 ◽  
Author(s):  
Hanwei Ren ◽  
Rikard Tröger ◽  
Lutz Ahrens ◽  
Karin Wiberg ◽  
Daqiang Yin

Abstract Background The vast occurrence of organic micropollutants in surface waters has raised concerns about drinking water safety and public health. The Tai Hu Basin region in China, a typical developing and populous area, is facing the challenge of water pollution. To ensure drinking water safety, the knowledge on how treatment techniques and raw water quality affect the quality of finished water must be improved. The aim of the current study was to evaluate drinking water quality in relation to source water origin and treatment strategies. Five drinking water treatment plants (DWTPs), using three different source waters in the Tai Hu River Basin, (i) Yangtze River, (ii) Wetland River Network, and (iii) Lake Tai Hu, were studied by analyzing 291 micropollutants in raw and finished water.Results Major differences in water characteristics were observed among the source waters. The dominating group of micropollutants in the River Network was pesticides, while Yangtze was mainly polluted by flame retardants. The total concentration of poly- and perfluoroalkyl substances (PFASs) in Tai Hu water was far higher than in others. In total, 51 compounds were detected in finished water, with an overall average total concentration of 730 ± 160 ng L -1 . The removal efficiency of the detected compounds in the DWTPs averaged 24 ± 149%, which highlights the major challenge for the DWTPs to remove emerging organic micropollutants through current treatment processes.Conclusions Our study showed that if the source water contains high levels of PFASs and organophosphorus flame retardants, even advanced treatment procedures are inefficient in removing the micropollutants, and the finished water may contain cumulative levels in the mg L -1 range. On the other hand, if pesticides and pharmaceuticals dominate, high overall treatment efficiencies may be obtained if using advanced treatment techniques. DWTPs are advised to use advanced treatment techniques or alternative water sources to guarantee the safety of drinking water. As surface water systems are highly impacted by upstream activities, efforts should also be made in the comprehensive water sector for improved surface water quality.


2003 ◽  
Vol 47 (3) ◽  
pp. 1-6 ◽  
Author(s):  
R. Holme

In May 2000, Escherichia coli 0157:H7 and Campylobacter jejuni contaminated the drinking water supply in Walkerton, Ontario. Seven people died and over 2,000 were ill as a result. The Ontario Provincial Government set up a judicial Inquiry into the circumstances surrounding the outbreak and also moved quickly to introduce a new Drinking Water Regulation that incorporated some significant requirements for drinking water providers. The Inquiry itself was in three parts: (a) part 1 related to the events that occurred in Walkerton and why the water contamination occurred; (b) part 1A related specifically to the role of the Provincial Government in the event; and (c) part 2 related to the future of drinking water safety in Ontario with potential to influence regulation on a wider basis. A number of other actions were taken after Walkerton. In August 2000, the Ontario Government, through the Regulatory body, the Ontario Ministry of the Environment (MOE) (a) re-issued and revised the Ontario Drinking Water Objectives (ODWO) as the Ontario Drinking Water Standards (ODWS) and (b) introduced new regulations governing drinking water in Ontario - the Ontario Drinking Water Protection Regulation. One of the key features of the Drinking Water Protection Regulation was the requirement to produce an independent Engineers’ Report on all water systems. This paper provides a unique perspective on the Walkerton tragedy and its aftermath. The author was active in many aspects of the resulting activity (Chair of the Ontario Water Works Association's (a section of the AWWA) Special Committee involved in Part 2 of the Walkerton Inquiry; author of several of the Engineers’ Reports mandated by Regulation; reviewer on behalf of the Regulator of Engineers' Reports submitted by others). The Engineers’ Reports were of interest because (1) the drinking water providers (mostly municipalities) were mandated by regulation to complete the Reports by specific dates and are paying for the Reports, (2) the work had to be done by a registered professional engineer who is not an employee of the owner or the operator if a different entity and (3) the engineer had to sign a declaration that the Regulator could rely on the accuracy of the Report. In other words, the Municipality retained the Engineer and paid them to produce the Report - the Engineer essentially carried the liability while the Regulator had the final say in the acceptability of the Report, a sort of eternal triangle of responsibilities. The paper will outline how the drinking water profession in North America worked together to provide the Walkerton Inquiry with the benefit of its experience and knowledge of best practices to the benefit of consumers and the drinking water providers. It will also outline the procedures adopted to produce the independent Engineers’ Reports and how the findings are being applied to further improve drinking water safety in Ontario, across Canada and in similar situations around the world.


2007 ◽  
Vol 5 (S1) ◽  
pp. 107-118 ◽  
Author(s):  
P. W. M. H. Smeets ◽  
J. C. van Dijk ◽  
G. Stanfield ◽  
L. C. Rietveld ◽  
G. J. Medema

Quantitative Microbiological Risk Assessment (QMRA) is increasingly being used to complement traditional verification of drinking water safety through the absence of indicator bacteria. However, the full benefit of QMRA is often not achieved because of a lack of appropriate data on the fate and behaviour of pathogens. In the UK, statutory monitoring for Cryptosporidium has provided a unique dataset of pathogens directly measured in large volumes of treated drinking water. Using this data a QMRA was performed to determine the benefits and limitations of such state-of-the-art monitoring for risk assessment. Estimates of the risk of infection at the 216 assessed treatment sites ranged from 10−6.5 to 10−2.5 person−1 d−1. In addition, Cryptosporidium monitoring data in source water was collected at eight treatment sites to determine how Cryptosporidium removal could be quantified for QMRA purposes. Cryptosporidium removal varied from 1.8 to 5.2 log units and appeared to be related to source water Cryptosporidium concentration. Application of general removal credits can either over- or underestimate Cryptosporidium removal by full-scale sedimentation and filtration. State-of-the-art pathogen monitoring can identify poorly performing systems, although it is ineffective to verify drinking water safety to the level of 10-4 infections person−1 yr−1.


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