Hi all…Health Canada has posted a request for public comment on the draft document entitled “Guidance on sampling and mitigation measures for controlling corrosion.” They indicate that it “has been developed with the intent to provide regulatory authorities and decision-makers with guidance on sampling and mitigation measures for controlling corrosion in drinking water distribution systems. The document is being made available for a 60-day public consultation period.” Note that the deadline for public comment is Feb 15, 2023.

Comments can be sent via email to Health Canada at water-eau@hc-sc.gc.ca.

Bill

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Draft guidance on sampling and mitigation measures for controlling corrosion

PDF 

Executive summary

“Corrosion is a common issue in Canadian drinking water supplies. Corrosion is the deterioration of a material, usually a metal, that results from a reaction with its environment. In drinking water distribution systems, materials that could be affected by corrosion and release increased amounts of contaminants (specifically metals such as lead) include metal pipes (e.g., lead service lines) and fittings. There are no direct health effects linked to corrosion in distribution systems, but corrosion may cause the release of contaminants that would be a concern for the health of Canadians. The main contaminant of concern is lead, for which the key health endpoint of concern is the reduction in intelligence quotient (IQ) scores in children. Lead is used as the trigger to initiate corrosion control programs to control or mitigate its release. Corrosion control treatment can effectively minimize lead concentrations at the point of consumption. However, when water is supplied through a lead service line, treatment alone may not be sufficient to reduce lead to concentrations below Health Canada’s maximum allowable concentration (MAC) of 0.005 mg/L (5 µg/L). Therefore, the removal of the full lead service line is likely the most effective and most permanent solution.

In this document, corrosion refers to the internal corrosion of the distribution system and not external corrosion of the infrastructure. Additionally, “corrosion control” refers to the action of controlling or mitigating the release of metals, primarily lead, that results from the corrosion of materials in drinking water distribution systems. Information on components of a corrosion control program is provided. However, detailed operational aspects such as developing a corrosion plan or removal of lead service lines are outside the scope of this document…Microbiologically influenced corrosion is briefly discussed but detailed information is beyond the scope of this document.

Although corrosion itself cannot readily be measured by any single reliable method, the lead levels at a consumer’s tap can be used as an indication of corrosion. Corrosion control programs will vary depending on the responsible authority. They can range from extensive system-wide programs implemented by the water utility to localized programs implemented by a building owner, to ensure a safe and healthy environment for the occupants of residential and non-residential buildings.

This guidance document was prepared in collaboration with the Federal‑Provincial‑Territorial Committee on Drinking Water and assesses all available information on corrosion control in the context of drinking water quality and safety.”

Assessment

“The intent of this document is to provide responsible authorities, such as municipalities and water suppliers, with guidance on assessing corrosion and implementing corrosion control measures for distribution systems in residential settings to minimize exposure to lead. It also provides sampling protocols and corrective measures for multi-dwelling buildings, schools, day care facilities and office buildings for those authorities, such as school boards, building owners or employers, that are responsible for the health and safety of the occupants of such buildings.

This document outlines the steps that should be taken to reduce population exposure to lead, which may also reduce the consumer’s exposure to other corrosion-related contaminants such as copper. Concerns related to other contaminants whose concentrations may be affected by corrosion, such as iron, are also briefly discussed.

This guidance is intended to complement the information provided in the Guideline Technical Document of the Guidelines for Canadian Drinking Water Quality for lead.”

Hi all…some of you will have received this latest Health Canada guidance announcement but it may have gone unnoticed as it was circulated on Dec. 24. It is entitled “Guidance For Providing Safe Drinking Water in Areas of Federal Jurisdiction” and is very timely. The document exceeds 100 pages in length and is quite detailed.

The PREFACE indicates that “most drinking water supplies in Canada are under provincial or territorial jurisdiction and have regulations, policies and/or standard operating procedures to follow. Federal departments are responsible for the safety of drinking water provided to consumers in areas of federal jurisdiction. Federal legislation establishes the Guidelines for Canadian Drinking Water Quality (GCDWQ) as the prescribed standards but does not provide guidance on their implementation. This document is intended to provide technical guidance to assist federal departments meet their legislative obligations. It takes into consideration the unique circumstances faced by many departments in order to best protect human health. While fully achieving the guidance in this document is the end goal, the focus should remain on the achievement of incremental improvements over time as an indicator of success.”

Section 2.5 (Roles and responsibilities in the federal jurisdiction) concisely addresses some questions I had stating: “No single federal department has overall authority for drinking water quality on federal lands. Health Canada provides leadership, as well as guidance upon request, but has no mandate to ensure safe drinking water in the federal house. Each department or responsible authority is in charge of implementing a drinking water program in areas within its mandate and is accountable for carrying out its duties. Each department should define who is responsible for drinking water management in their facilities; each person involved with drinking water programs needs to know what is expected of them and their level of responsibility. Departments should make sure all required tasks have been assigned to specific, qualified staff.”

Bill

Hi all…I just came across an open access paper published in 2014 which I hadn’t seen previously but is probably as relevant today as it was then. I am pretty familiar with the patchwork of guidelines and regulations in Canada but this paper has the best collection of details that I have ever come across. For example, their “review identifies key differences in the regulatory approaches to drinking water quality across Canada’s 13 jurisdictions. Only 16 of the 94 CDWQG are consistently applied across all 13 jurisdictions; five jurisdictions use voluntary guidelines, whereas eight use mandatory standards.” See also the statement in the abstract that states Canada doesn’t comply with the “World Health Organization’s (WHO) recommendation that all countries have national, legally binding drinking water quality standards.”

Bill

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Drinking Water Quality Guidelines across Canadian Provinces and Territories: Jurisdictional Variation in the Context of Decentralized Water Governance

Gemma Dunn, Karen Bakker and Leila Harris

https://www.mdpi.com/1660-4601/11/5/4634/htm

International Journal of Environmental Research and Public Health 2014, 11, 4634-4651; doi:10.3390/ijerph110504634

Abstract

“This article presents the first comprehensive review and analysis of the uptake of the Canadian Drinking Water Quality Guidelines (CDWQG) across Canada’s 13 provinces and territories. This review is significant given that Canada’s approach to drinking water governance is: (i) highly decentralized and (ii) discretionary. Canada is (along with Australia) only one of two Organization for Economic Cooperation and Development (OECD) member states that does not comply with the World Health Organization’s (WHO) recommendation that all countries have national, legally binding drinking water quality standards. Our review identifies key differences in the regulatory approaches to drinking water quality across Canada’s 13 jurisdictions. Only 16 of the 94 CDWQG are consistently applied across all 13 jurisdictions; five jurisdictions use voluntary guidelines, whereas eight use mandatory standards. The analysis explores three questions of central importance for water managers and public health officials: (i) should standards be uniform or variable; (ii) should compliance be voluntary or legally binding; and (iii) should regulation and oversight be harmonized or delegated? We conclude with recommendations for further research, with particular reference to the relevance of our findings given the high degree of variability in drinking water management and oversight capacity between urban and rural areas in Canada.”

Photo by engin akyurt on Unsplash

Hi all…there continues to be a number of non traditional drinking water papers being published recently. A new paper entitled “A pilot study on the feasibility of testing residential tap water in North Carolina: implications for environmental justice and health” got my attention. The study used a “14-in-one dipstick test designed to measure trace amounts of heavy metals, non-metallic elements, and physicochemical water properties in drinking water in 70 homes.” The article offers a very different perspective, using citizen scientists and addressing implications for environmental justice and health. This makes it an interesting read but I am going to focus on the tap water data aspect here.

I’m guessing that most would expect to see that lead would figure prominently and it does, along with chromium and mercury being in the top three. In fact, the abstract reports that mercury was detected above the USEPA maximum contaminant level (MCL), of 0.002 mg/L (2 ppb), more frequently than any other parameter! I checked to see what the USEPA suggested are sources of mercury and they indicate erosion of natural deposits; discharge from refineries and factories;  and runoff from landfills and croplands.

However, the finding was so unusual that I read the paper carefully to try and understand what made this study so different. In fact, the abstract is not consistent with the text which indicates about 27% of homes had lead levels above the USEPA MCLG of zero. Approximately 3% of all homes indicated “precarious levels of lead above 5 ppb.” About 55% of homes had “high levels of chromium, above the USEPA drinking water MCL of 0.10 ppm.” About 7% of all homes tested at levels above the USEPA MCLG of 0.002 ppm of mercury. I contacted the authors who, as it turns out, noticed the inconsistency earlier and had contacted the journal to make the correction. Unfortunately, it has not been done to-date. Nonetheless, the finding that mercury was present and exceeded the USEPA MCL in 7% of samples was still unexpected (at least for me). So, just to be clear, in 50%, 25%, and 7% of water samples tested, the concentrations of chromium, lead, and mercury, respectively, were higher than USEPA drinking water standard. So while mercury was third highest, chromium exceedances (55%) were higher than lead (27%)!

There were other contaminants detected, for example ~ 17% of homes exceeded the US-EPA MCL for nitrate, which is a big deal. Note that the study reports exceedances of MCLs but also maximum contaminant level goals (MCLG), the regulatory implications of each being quite different.

Bill

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A pilot study on the feasibility of testing residential tap water in North Carolina: implications for environmental justice and health

Love Odetola, Stephen Sills, and Sharon Morrison

Journal of Exposure Science & Environmental Epidemiology (2021) 31:972–978; https://doi.org/10.1038/s41370-021-00352-2

“BACKGROUND: In 2015 alone, community water systems serving about 21 million Americans violated the United States Environmental Protection Agency’s (US-EPA) water quality standards. While water at community treatment and distribution centers is regularly monitored and tested, little is known about pollutants in the water systems at the household level.

AIMS: This pilot study assessed the feasibility of (1) testing for the presence and concentration of 14 contaminants and physicochemical parameters in household tap water in a low-income neighborhood and (2) using community engagement for recruitment and citizen science approaches to data collection.

METHODS: We used a multistage approach that included geo-mapping to delineate testing sites, community engagement for recruitment and citizen science approaches to increase the response rate. We used a 14-in-one dipstick test designed to measure trace amounts of heavy metals, non-metallic elements, and physicochemical water properties in drinking water in a sample of 70 homes.

RESULTS: In 50%, 25%, and 7% of water samples tested, the concentration of mercury, lead, and chromium, respectively, were higher than US-EPA drinking water standards. Citizen science approaches were effective for increasing response rates and low income household participation in water quality testing.

SIGNIFICANCE: The overlap between poverty, older homes, and high concentrations of potentially toxic metals in drinking water presents concerns for community health. Our pilot community engagement and citizen science approaches are likely scalable and would be of benefit to both the scientific community and to municipalities with constrained budgets. Future studies may examine the role of the principles of environmental justice in the distribution and prevalence of toxic elements in drinking water.”

Hi all…there are several best practices (and guidelines and regulations) for flushing and ‘disinfecting’ drinking water distribution piping following installation or repair (e.g. AWWA Standard C651-05 Disinfecting Water Mains, and the Watermain Disinfection Procedure in Ontario). A just published Dutch study on the topic using E. coli, Clostridium perfringens spores, and phiX174 (an enteric virus surrogate)reports that “On average, flushing removed 1.5–2.7 log microorganisms from the water, but not the biofilm…Flushing velocity (0.3 or 1.5 m/s) did not affect the efficacy.” Perhaps not surprisingly they conclude that “Flushing alone is thus not sufficient after high risk repair works or incidents, and shock chlorination should be considered to remove microorganisms to ensure microbiologically safe drinkingwater.”

The AWWA and Ontario standards prescribe that shock chlorination and flushing both be used but as far as I can see there is no discussion of flushing velocity (just flushing until background chlorine residual is reached).

This is an open access article if you’d like to see more.

Bill

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Efficacy of Flushing and Chlorination in Removing Microorganisms from a Pilot Drinking Water Distribution System

Nikki van Bel, Luc M. Hornstra, Anita van der Veen and Gertjan Medema

Water 2019, 11, 903; https://www.mdpi.com/2073-4441/11/5/903

Abstract

“To ensure delivery of microbiologically safe drinking water, the physical integrity of the distribution system is an important control measure. During repair works or an incident the drinking water pipe is open and microbiologically contaminated water or soil may enter. Before taking the pipe back into service it must be cleaned. The efficacy of flushing and shock chlorination was tested using a model pipe-loop system with a natural or cultured biofilm to which a microbial contamination (Escherichia coli, Clostridium perfringens spores and phiX174) was added. On average, flushing removed 1.5–2.7 log microorganisms from the water, but not the biofilm. In addition, sand added to the system was not completely removed. Flushing velocity (0.3 or 1.5 m/s) did not affect the efficacy. Shock chlorination (10 mg/L, 1–24 h) was very effective against E. coli and phiX174, but C. perfringens spores were partly resistant. Chlorination was slightly more effective in pipes with a natural compared to a cultured biofilm. Flushing alone is thus not sufficient after high risk repair works or incidents, and shock chlorination should be considered to remove microorganisms to ensure microbiologically safe drinking water. Prevention via hygienic working procedures, localizing and isolating the contamination source and issuing boil water advisories remain important, especially during confirmed contamination events.”