Excess levels Haloacetic Acids identified in Thames Centre drinking water


Please find attached PDF for the official media release. 

October 12th, 2022

London, ON – The Middlesex-London Health Unit and the Municipality of Thames Centre announced today that water in the town’s distribution system exceeded the Province’s maximum acceptable concentration for haloacetic acids (HAA). HAAs are a group of byproducts that can form in drinking water systems when chlorine compounds used in the disinfection process react with naturally occurring organic material present in the water. Under Ontario’s Drinking Water Quality Standards, the Ministry of the Environment, Climate and Parks requires that the rolling annual average HAA concentration in a drinking water system not exceed 80 micrograms per litre, or 80 parts per billion. Based on testing done four times a year, the most recent rolling annual average HAA concentration for Thames Centre’s drinking water was 82.6 micrograms per litre.
While Thames Centre has been sampling the water in its distribution system and monitoring the level of HAAs for several years, it’s only since January 1, 2020, that municipalities have been required to notify public health when the maximum acceptable concentration is exceeded.
“These findings do not constitute an immediate health risk to those who use the water in Thames Centre, but they are higher than the provincial standard, so it’s important that we are transparent and let the community know,” says Dr. Alex Summers, Medical Officer of Health with the Middlesex-London Health Unit. “While there is data to suggest that drinking water with elevated levels of HAAs over the course of a lifetime may lead to a slightly increased risk of cancer, in this case, the exceedance is very low. Given the many risk factors we are exposed to every day, this situation would not lead to an increase in an individual’s overall risk of developing cancer.”
The Health Unit was notified of the exceedance almost two weeks ago and has been working with the municipality and the Ministry of the Environment, Climate and Parks to determine next steps and the mitigation measures that can be put in place.
“Thames Centre has adjusted their day-to-day operations in attempt to reduce these levels,” says Jarrod Craven, Director of Public Works with the Municipality of Thames Centre. “We are actively seeking alternatives to reduce the disinfection by-product precursors in the treatment process at the Water Treatment Facility.”
Chlorination has long been used to eliminate pathogenic organisms from drinking water systems and has led to the virtual elimination of waterborne disease. The health benefits associated with the chlorination of drinking water far outweigh the potential risks associated with slightly elevated levels of HAAs within the drinking water system.
Media Contact:
Morgan Lobzun, Communications Coordinator, Middlesex-London Health Unit, 519-617-0571
Alan Bushell Legislative/Communications Officer, Municipality of Thames Centre, 519-268-7334 Ext. 254
Dr. Alex Summers, Medical Officer of Health, Middlesex-London Health Unit
Jarrod Craven, Director of Public Works, Municipality of Thames Centre