Water tasting weird in south London? It's safe to drink, officials say

Residents in south London might notice that their drinking water has a taste or odour to it this time of year, but officials with the City of London say it's still safe to consume.

The taste and odour change is seasonal, the city said in a statement on Wednesday. The temporary change is anticipated to last about a week.

"The change is caused by naturally occurring organic compounds in Lake Erie," the city said. "Residents can reduce the taste or odour with a cartridge water filter, or by placing a water pitcher in the fridge before consumption."

London's drinking water comes from two Great Lakes. About 85 per cent comes from Lake Huron, and the remaining 15 per cent comes from Lake Erie. The Elgin Area Water Treatment Plant (WTP) regularly collects samples to test the water quality, said the city, and can make adjustments as needed if conditions change.

"Consumers sometimes describe their water as tasting or smelling earthy, musty, mouldy, swampy or organic," Elgin Area WTP said in another statement. "Some people are sensitive to the taste and odour, but others may not notice it at all."

The taste and odour are caused by geosmin and 2-Methylisoborneol (MIB) in the raw lake water. They are harmless, naturally occurring organic compounds produced by algae or cyanobacteria in surface water during late summer and early fall.

More than 12,000 water quality tests are conducted annually to ensure the municipality's water quality and taste.

Residents can learn more about the process of treating London's drinking water at london.ca/water.