This Chemical Turned Water Pink in a Canadian Town. But We Actually Need It

Water turned pink in a small Canadian town this week after a faulty valve allowed the disinfectant potassium permanganate to seep into the water supply. The color looks alarming, but the chemical actually plays an important role protecting the water we drink from everything from minerals to invasive species.

Water treatment facilities typically add potassium permanganate early in their process at the time of untreated water intake, according to the EPA. The chemical reacts with iron and manganese in the water to form solids that are filtered out later in the water treatment process. Water is typically also treated with a chlorine disinfectant. Potassium permanganate can be toxic at high concentrations, but no health problems were reported in the town.

In recent years, water treatment facilities have also used potassium permanganate to protect water sources from zebra mussels, an invasive species that has caused trouble in the Great Lakes and waterways across the country.

But all of that information was likely of little solace at first to the residents of Onoway, in Alberta, who took to social media to voice their surprise and concern at bright pink water running from their faucets.

The valve was fixed and the town’s mayor, Dale Krasnow, apologized to residents, promising to improve communication should something similar happen again in the future.

Write to Justin Worland at justin.worland@time.com.