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Health Unit weighs in on Tottenham’s water situation

April 26, 2019   ·   0 Comments

By Brock Weir

A standing-room-only crowd attended an open house on water quality issues in Tottenham.

It was an opportunity for residents to learn and ask questions but, in some cases, the Simcoe Muskoka Health Unit could not provide a “complete reply.”

On Tuesday, the Health Unit announced it had updated its website to provide more fulsome answers to questions raised on April 2.

While full details can be found at, their answers to residents’ queries are provided below.

Can people receive more frequent results of municipal THM sampling? i.e. on a monthly or weekly basis?

If residents are interested in receiving information about drinking water sampling results they can contact the Town of New Tecumseth to request this information.  However, moment-by-moment results aren’t indicative of the overall level of risk for THMs; when brought into a larger set of data, the longer term running average is the real indicator of health risk/safety. Levels are presently below the Ontario Drinking Water Standard now, but SMDHU would prefer they be even lower.

It is important to know that the Ontario Drinking Water Standard requires the annual rolling average of THMs to be below 100 μg / litre (100 micrograms per litre, or 0.1 mg per litre) of drinking water but also as low as can reasonably be achieved, based on samples taken throughout the community. Periodic increases in THMs above 100 μg / L have not been found to be associated with negative health impacts.

What private home filtration is available to remove THMs from water?

Ideally, the THM levels in the water should be low enough that you don’t need to purchase additional home filtration units.

If you choose to add a treatment device to your home drinking water supply we strongly recommend using only equipment that has an approval stamp from NSF International or ANSI (American National Standards Institute).The NSF website contains information about home drinking water filters.

Health Canada has indicated that THMs may be reduced from the drinking water supply by both activated carbon filters and reverse osmosis systems. These systems can be installed at the faucet, or wherever water enters the home.

It is important that you carefully monitor and maintain the equipment as per the owner’s manual. Filters may need to be replaced frequently when there are high levels of iron or other solids, sometimes referred to as turbidity. Failure to maintain filters in good working condition can result in bacterial overgrowth and contamination of drinking water.

What is the provincial average for THMs, and how does that compare to Tottenham?

The Ministry of the Environment, Conservation and Parks informs us they do not have a readily available means of averaging THMs in all the drinking water systems in Ontario. As source waters and drinking water treatment systems vary so much across the province, such a value would be an unreliable baseline to compare local results to. The health-based Ontario Drinking Water Standard for THMs is the only meaningful value for comparative purposes.


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