PUBLISHED: 29 August 2018      Last Edited: 29 August 2018

Municipal treatment of drinking water is the key to community health, but it can have hidden toxins as well

by Emily Walsh in collaboration with the Alberta WaterPortal

Clean drinking water is something many of us take for granted, while others go to great lengths to protect and restore our natural water resources. The Centers for Disease Control and Prevention (CDC) estimates that 780 million people around the world lack access to a treated water source.1 This does not take into account the treated water billions of people have access to that still contains harmful toxins. Below is a list of toxins sometimes found in tap water and how they get there.


Studies have shown that consuming significant levels of lead may lead to cognitive and nervous system malfunction, especially in children.2 Lead is a naturally-occurring heavy metal that can enter drinking water in a variety of ways. As a metal found in the environment, soil erosion or mining can bring traces of lead into water ways. However, lead primarily enters water from the disposal of manufactured products. In the past, lead has been used in various consumer products ranging from paint and toys, to gasoline and ceramics. Some water distribution systems also incorporated lead and may be tainting drinking water due to corrosion of pipes, service lines, solder and fittings. Canada has ruled out the installation of lead pipes since the mid 1970s, however it may still be present in systems built before this time.

Although lead is considered toxic, trace amounts are present throughout the environment. Lead is highly regulated and water providers ensure that less than 0.01 mg/litre is consumed

Click here to read more on the facts and misconceptions about lead in our drinking water.

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Asbestos is a natural mineral that was used globally in the construction and manufacturing industries during the mid-1900s. It was commonly added to cements to increase heat resistance, and was included in a large portion of water distribution systems. Asbestos-cement (AC) pipes have been around for upwards of a century and these pipes may degrade over time, releasing asbestos into our water supplies. The use of asbestos in building construction material has been banned in Canada due to the health impacts of inhaling asbestos fibers. Inhaling airborne asbestos fibers is linked to lung cancer, mesothelioma, and other diseases, but studies on consuming it in food or water have not shown any evidence of negative health impacts.

Although there is no evidence of negative health impacts from consuming asbestos in water (rather than inhaling it), there is still concern (due to its association with gastrointestinal diseases and cancers like mesothelioma). There is no guideline for asbestos in Canadian Drinking Water Quality Guidelines due to there being no evidence of negative health effects from asbestos in water.3 There are small amounts of asbestos found in most drinking water.4

Disinfection By-Products

Disinfection by-products, or DPBs, are formed in reaction to organic compounds combining with certain chemicals like chlorine that are used to purify water. Chlorination has become the most widely-used form of water treatment today,5 and has been proven to reduce waterborne illnesses. Chlorine’s reactions with other components in water has been known to produce DBPs like trihalomethanes and chlorate. At high concentrations DBPs have been linked to a range of gastrointestinal issues, including cramping and vomiting, as well as lasting health conditions like liver cancer.

DBPs are heavily regulated in Alberta’s drinking water. Treatment plants work to keep DBPs like trihalomethane to less than 100 parts per billion. It is nearly impossible to fully rule out DBPs while maintaining the disinfection process, but water treatment managers constantly work to practice disinfection that limits the amount of harmful molecules produced.

Click here to learn more about DBPs


Pesticides come in a variety of forms, but all are classified as chemicals used to control vermin like weeds, insects and bacteria. Most are man-made products, but some exist naturally. Pesticides enter drinking water from rain runoff, soil absorption, or direct application to lakes or wetlands. The risks of pesticide consumption range from no sizable effect to organ failure or cancer at high doses.

Since the implementation of The Stockholm Convention on Persistent Organic Pollutants in 2004, many pesticides have been restricted due to their harmful effects. Municipal water systems frequently test for high levels of pesticides, and while some pesticides have been shown to pose a threat to human health and the natural environment, many others have not been studied adequately to confirm or deny negative impacts. Ideally, pesticides with negative and unknown impacts would be used as little as possible. Although pesticides are commonly found in Albertan source water, most cases reported levels of contamination under the maximum allowable concentration in accordance to the Alberta Environment and Parks’ Surface Water Quality Guidelines.6

Click here for more information on pesticides in drinking water.

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So what do we do about it?

Despite the substances discussed in this article having varying degrees of toxicity, our communities benefit by having large-scale municipal water treatment systems, therefore it is better to monitor and manage the concentration of these known substances than to stop the water treatment processes. Waterborne parasites, bacteria and viruses have been, and continue to be a significant cause of mortality for people in communities around the world. For this reason, a clean drinking water supply is one of the most important municipal services for a community to maintain.

Studies indicate that diverse types of human produced contaminants are increasing in waterways around the world. Due to the challenges associated with filtering some types of contaminants out of water, our best strategy is to find ways to limit or prevent them entering the water in the first place. Emphasizing water management and quality will help improve our drinking water and health, as well as the health of our environment. Sustainable practice is more important than ever, especially in the filtration and maintenance of water supplies. Monitoring and protecting the source water will help maintain good quality drinking water, and healthy ecosystems and natural resources.

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Emily Walsh utilizes community outreach to bring attention to the dangers of asbestos exposure and its impact throughout the world. Emily dedicates much of her time to raising awareness about mesothelioma cancer through social media and blogging, working with like-minded organizations to spread the word. Her goal is to one day see a global ban on asbestos.



1. Centres for Disease Control and Prevention. (2016, April 11) Global WASH Fast Facts. Global Water, Sanitation, and Hygiene. 

2. Health Canada. (2017) Lead in Drinking Water. Prepared by the Federal-Provincial-Territorial Committee on Drinking Water. Government of Canada. 

3. CAREX Canada. (2018, June) Asbestos – profile. 

4. World Health Organization. (2003)  Asbestos in Drinking-water: Background document for development of WHO Guidelines for Drinking-water Quality. World Health Organization, Gevneva 

5. Water Research Centre (2018) Chlorination of Drinking Water: Private Well Owner and Small System Operator Guide. 

6. Government of Alberta (2018) Environmental quality guidelines for Alberta surface waters. Water Policy Branch, Alberta Environment and Parks, Edmonton, Alberta.