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Taste and Odour

Geosmin and Methyl-Isoborneol (MIB) are naturally occurring compounds that have a very strong, earthy taste and odour. Geosmin can be detected by human noses at very low levels.

Tay Township routinely monitors weekly for Geosmin and MIB in the water supply. These compounds are generally present in drinking water, however not at noticeable levels.

Generally, Geosmin becomes an aesthetic issue for customers when levels are in the range of 20-30 nanograms (one millionth of a milligram) per litre, but some people who are particularly sensitive may notice it at levels above 10.

What are the effects of Geosmin and MIB?

Geosmin and MIB produce a musty, earthy smell and taste in drinking water, however are not harmful at levels present in drinking water.

What causes increased levels of Geosmin and MIB?

Due to the increased surface water temperature of Severn Sound some kinds of algae and bacteria present in surface water naturally produce Geosmin and MIB. Increased concentrations of these microorganisms can cause an increase in Geosmin and MIB concentrations above the taste and odour threshold.

What can be done about Geosmin and MIB?

Geosmin and MIB cannot be removed from water using normal treatment processes that are currently employed at the Tay Area Water Treatment Plant. As such, we experience this taste and odor issue annually to varying degrees dependant on the surface water temperature.

The Environmental Assessment completed for the current Tay Area Water Treatment Plant upgrade program considered and addressed these taste and odour issues. Related improvements will be considered as part of the Phase 2 design which is currently underway. Phase 2 construction is anticipated for 2020.

In the short-term, using a home granulated activated carbon charcoal filter for your drinking water may help to reduce the effects of this taste and odour issue.