Overview

NWT drinking water is treated with chlorine to make sure it is safe from harmful microorganisms such as bacteria and viruses. When chlorine reacts with natural organic matter in lakes and rivers, it can form small amounts of substances called disinfection by-products (DBPs).

The benefits of disinfecting drinking water are much greater than the possible risks of DBPs. Water is tested regularly across the NWT to make sure it remains safe to drink.

This page explains what DBPs are, how they are monitored, and steps residents can take to reduce exposure.

Why DBPs matter

Disinfection by-products (DBPs) are created when chlorine reacts with natural organic matter, like leaves or vegetation, in water sources.

The most common DBPs are trihalomethanes (THMs) and haloacetic acids (HAAs). Levels of these substances may rise in the summer and fall when there is more organic matter in the environment.

Health effects of DBPs

Being exposed to DBPs over short periods of time, such as through drinking, bathing, or showering, is not considered harmful.

Over many years, regular exposure to drinking water with high levels of DBPs may increase the risk of certain cancers, such as bladder cancer.

It takes long-term, high-level exposure to put health at risk.

Monitoring in the NWT

All public water supply systems must meet the Public Health Act and the Water Supply System Regulations. These laws require water supply system operators to provide water that is safe for human consumption.

Testing includes regular sampling for THMs.  At least four samples are required to be taken each year.

Guideline levels

The NWT follows the Guidelines for Canadian Drinking Water Quality, which sets maximum acceptable concentrations (MACs) for DBPs:

Test results below the MAC are not expected to cause health effects. If results are above the MAC, additional monitoring and corrective actions may be taken.  

Reducing your exposure at home

If you are concerned about DBPs in your water, you can:

• Use a certified water filter (NSF/ANSI Standard 53):
  • pitcher-style filters
  • faucet or refrigerator filters
  • follow the manufacturer’s instructions for replacing filters
• Use water from another source, such as bottled water.
• Never drink untreated water straight from a lake or river.
• Take shorter baths and showers:
  • baths: less than 30 minutes
  • showers: less than 10 minutes
• Improve ventilation when bathing or showering by opening windows or using a fan.

More Information

See the Government of Canada’s fact sheet on disinfection by-products in drinking water.