Skip to Main Content Health Care Professionals Haldimand-Norfolk Health Unit Search


Lake Erie Drinking Water Taste and Odour Concerns


SIMCOE SEPTEMBER 9, 2013 – Norfolk County residents that receive water from the Port Dover and Port Rowan Drinking Water Treatment Plants may notice a musty/earthy taste or odour in their drinking water.

Taste and odour episodes are a natural phenomenon caused by seasonal biological changes in the source water, which produces odour-causing chemical compounds, called geosmin and 2-methylisoborneol (MIB), that can be detected by humans at very low levels. Geosmin and MIB are produced by the bacteria Actinomycetes and some species of blue-green algae, though the exact organisms are not known. Most municipalities in Ontario which obtain their water supply from surface water sources experience this problem periodically in the summer or early fall.
The unpleasant taste and odour may make you think that the water is “off” and not safe to drink.Tap water supplied via the municipal water supply systems remains safe to drink during these episodes.Seasonal taste and odour in drinking water is not a threat to public health.
Norfolk County is making every effort to reduce the impact of taste and odour episodes. The Water Treatment Plants are equipped with various filtration systems designed to reduce the effects of taste and odour but may not eliminate it entirely. The taste and odour episodes vary from one year to another, therefore the problems cannot be solved rapidly.


Frequently Asked Questions

What causes the musty taste and odour in our drinking water?

The odour causing compounds are more prominent during extended warm temperatures. When temperatures reach 19oC and above, naturally occurring compounds which can create a musty odour or taste are formed. Two compounds called Geosmin and 2-Methylisoborneol (2-MIB) are responsible for a musty or earthy odour that is detectable by some persons in concentrations as low as a few parts per trillion (ppt). (One ppt is equivalent to one drop of water in 1000 Olympic-sizes swimming pools.)

Where do these compounds come from?

Geosmin and MIB (2-Methylisoborneol) are produced in aquatic environments by cyanobacteria (blue-green algae) or mould-like, filamentous bacteria called actinomycetes. Very tiny concentrations of these compounds can create the earthy/musty taste and odours in water. Geosmin, the same substance that can be detected when rich soil is turned, is also found in some foods including beets.

Is the water safe to drink?

Yes. Norfolk County’s municipal drinking water customers are advised that the County’s drinking water is safe; this odour poses no health impacts and is strictly aesthetic. The County’s drinking water is sampled on a daily basis throughout the various systems to ensure its safety and compliance with the Safe Drinking Water Act.

When does the musty taste and odour occur?

Although occurrence frequencies are difficult to predict, a Geosmin peak generally can occur anytime from the end of August through November each year. In the past it had been thought that taste and odour events only occurred periodically. It is now understood that the events likely occur each year but the intensity can vary widely.

How long will the musty taste and odour last?

Depending on the weather temperatures, these tastes and odours could persist in our drinking water for a couple of weeks.

What can I do at home to reduce tastes and odours?

In home water filtration systems that use activated carbon can help reduce or eliminate the tastes and odours. Storing water in a loosely sealed glass container in the refrigerator can also be helpful.

For further information contact:
Bob Fields, Manager
Environmental Services Division
(519) 582-2100 ext 1500


Bob Fields, C.E.T.
Manager, Environmental Services Division
Public Works and Environmental Services Department
Norfolk County
Phone: (519) 582-2100 ext 1500
Fax: (519) 582-4571