Bright pink water flowed through Canadian town's taps prompting complaints from residents and forcing the mayor to issue and apology.

Caused by Potassium permanganate, a chemical used in the standard water treatment process, there was no significant health risk to the residents of Onoway, Alberta.

But Mayor Dale Krasnow said in a statement that the town "could have done a better job communicating what was going on."

Though water took on a startling pink hue on Monday, townspeople were not informed of the cause until the following morning.

Potassium permanganate is used worldwide to remove iron and hydrogen sulfide from water supplies. Hydrogen sulfide is corrosive and highly poisonous, and has a distinctive, foul odour of rotten eggs.

Potassium permanganate is relatively benign, although large quantities can cause skin irritation.

However, there are no reports of any adverse medical effects in Onoway. The small town has a population of around 1000, and is located 40 miles northwest of the city Edmonton.

Mayor Krasnow suggested the problem was caused by a faulty valve, "stuck allowing the potassium permanganate to get into our sump reservoir and thereby into the Town’s water distribution system."

He said: "Immediately and throughout this entire process our staff have been in contact with Alberta Environment, and today our discussions have included Alberta Health Services.

"We were never advised by Alberta Environment to issue a public advisory and all indications are that there was never a public health risk."

Townspeople were asked to keep all their taps running until water turned clear, flushing out the chemical agent from the system.

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Though he emphasised there was no cause for alarm, Mayor Krasnow apologised for the way the situation was handled.

He said: "Could the Town have done a better job of communicating what was going on yesterday to our community – absolutely, without a doubt. And we do apologize for that.