Water Supply – Taste and Odour

Hot weather can mean taste and odour problems for water.

During the late summer or early fall, residents may experience a noticeable smell and musty tasting water. This is caused by seasonal biological changes in Windermere Lake, which produces a naturally occurring, odour-causing chemical compound, called geosmin. Even at very low levels, geosmins can be detected by some people.

The unpleasant taste and odour may make you think that the water is "off" and not safe to drink. Be assured that during periodic taste and odour events, your water is safe. Seasonal taste and odour in drinking water is not a threat to public health.

If you should notice a taste and odour in your water during the summer or fall season, simple home remedies, such as keeping a jug of water in the fridge and adding ice cubes or some lemon juice to tap water should improve it.

What if my water tastes or smells funny?

In the late summer or early fall, you may notice an earthy, musty smell and taste in your tap water. Natural seasonal changes in Windermere Lake can cause this to happen. We're not alone, Lake Ontario and all the cities and towns that draw their water from there have the same problems. Lake water temperatures which can increase dramatically over the summer can result in increased numbers of algae. Certain types of algae produce compounds that can result in a noticeable odour or taste even at extremely low levels. One of these is geosmin which is usually measured in parts per trillion (one million millions). Humans can detect its presence in concentrations as small as 10 parts per trillion. These episodes can result in concentrations of more than 50 parts per trillion, a level at which the compound can be easily detected by most people in their tap water.

Is this water still safe to drink?

Yes, your water remains perfectly safe to drink. The only change is the presence of these taste and odour-causing compounds, at trace levels, which are not harmful to health. The treated water supply from Windermere Lake water is tested on a weekly basis to confirm the absence of harmful bacteria. Testing during these taste and odour episodes confirm that the quality of the water continues to be excellent.

Can the taste and smell be reduced?

To make the water taste better, try chilling it, adding ice cubes or squirting in a few drops of lemon juice.

How long does the taste and smell last?

The duration of past episodes have ranged from a few days to 11 days. It is impossible to predict, at the onset of an episode, how long it will last. Generally, as the lake water temperatures drop, the problem begins to disappear.

Why doesn't the water treatment process remove the problem?

Water treatment plants can make operational changes to reduce the taste and odour effects to some extent when they occur. While algae is specifically removed during the water treatment process, compounds such as geosmin are not easily eliminated.