Warmer temperatures, stagnant supply prompt Hamilton to add more chlorine to drinking water

The province is allowing Hamilton Water to go above its standard threshold after a surge in incidents in recent years where chlorine had degraded.

Warmer temperatures and stagnant liquid in the city’s distribution system have prompted Hamilton to up chlorine levels in its drinking water.

Director of water Nick Winters revealed the slight increase in the disinfectant is to tackle “chlorine degradation” – when the element dissipates through non-activity, increasing temperatures or a combination of both.

“When folks aren’t watering their lawns and using potable water … we have seen challenges over the past few years with chlorine degrading in some of the outer reaches of our system,” Winters explained.

He says the city resorted to flushing out much of the system in 2021, like the fire hydrant infrastructure, to replenish “old water” stuck in some areas.

Regular monitoring that year saw a higher number of adverse water quality incidents tied to low chlorine.

However, the city didn’t see the same issues in 2022 due to lower-than-normal precipitation and colder temperatures.

The city applied for and received approval in 2023 from the Ministry of the Environment (MECP) to increase levels of chlorine at the Woodward Water Treatment Plant as a backup to avoid similar issues experienced in 2021.

Winters says they’ll be bumping chlorine levels this summer to 2.9 milligrams per litre from the previous 2.7, and possibly going from 2.5 milligrams per litre to 2.7 in the winter months.