How do we know our water is safe to drink?
In the hot summer months, residents can expect typical, seasonal taste and odour changes to our municipal drinking water. These changes are most often a musty/earthy taste or odour to their drinking water or a noticeable increase in the taste/odour of chlorine. If you detect earthy or musty odours in your drinking water, please note that it is still safe to drink.
Many municipalities which get their water supply from surface water sources experience this problem periodically. While changes in the taste and odour may be unpleasant for some with a sensitive sense of taste and smell, these changes only affect the aesthetic qualities of the water and do not impact water safety. A boil water advisory would likely be the first sign of any genuinely unsafe drinking water situation for any reason.
What causes the taste odour occurrences?
Taste and odour occurrences caused by seasonal biological changes in the source water produce naturally occurring compounds, called Geosmin (GSM) and 2-methylisoborneol (2-MIB). Surface water can experience seasonally elevated levels of GSM and 2-MIB when aquatic vegetation dies and begins naturally decomposing. These occurrences happen especially during hot weather when water temperatures rise and the water levels are lower. Even very tiny concentrations of these compounds in water can result in a musty/earthy taste and odour. The solution requires higher levels of chlorination to treat.
We refer to this as taste and odour episodes. During these episodes, tap water supplied by the municipal water supply systems remains safe to drink and is not harmful to public health. Our water treatment plants are designed with processes to reduce the effects of taste and odour, but these may not eliminate it entirely.
When does the musty taste and odour occur?
Although occurrence frequencies are difficult to predict, these naturally occurring compounds generally can occur anytime from the end of August through November each year. It was previously understood that taste and odour events only occurred periodically. It is now believed that the events likely occur each year, but the intensity can vary widely.
Ways to reduce tastes and odours
Residents who experience taste and odour issues with their tap water can use an activated carbon water filter pitcher, such as a Brita, to help absorb the GSM which may further reduce or eliminate the taste and odour.