A temporary halt to chlorination in Kawerau risks contaminating the town's water supply with E. coli, the town's mayor says.

Kawerau District Council has stopped chlorinating the water because locals complained it was discoloured.

Chlorine was introduced to the town's system last July, after the Havelock North water contamination led to recommendations to chlorinate reticulated supplies.

Since then, Kawerau residents have had to deal with tap water sporadically turning yellow or brown, caused by the chlorine dislodging built-up bacteria in the pipes.

Mayor Malcolm Campbell said there had been hundreds of complaints over the colour of the water.

He clarified that the water from the spring was safe and had been treated but the issues arose once it went into the reticulation system.

"It's always been a concern of the council, especially since Havelock," says Malcolm.

"We've known that this was the writing on the wall once that did happen and we are concerned but we also know that this is probably the better way of going about getting down to the problem."

The council says while the water is still safe to drink, it will stop chlorination while it flushes the network and tries to clean the pipes by air scouring.

Malcolm says while the chlorine is stopped, there is a small chance E.coli may get into the supply.

"If you have not got chlorinated water in your reticulation system you run a risk of E. coli hitting you.

"In the past we've had low forms of E. coli and we've dosed it and it has gone away within days and then [it's] back to normal."

He told Checkpoint that previously, and for the last 40 to 50 years, three-day tests used to be conducted on the water supply and if any E. coli showed up, it was dosed.

"That's always been our concern with our water because we never used to chlorinate it. We've stopped the chlorine as of 1pm Tuesday afternoon, which has been having a bit of a reaction on our pipes to be honest."

Malcolm says the water will be regularly tested and any E. coli contamination would be caught and managed quickly.

He says once the cleaning is finished, the council will revisit chlorination.

He says even if the Health Ministry is to question the decision, he's prepared to defend it.

"I welcome them because I'll be the first one there leading the charge, to have them come into our community and tell them exactly where we stand and it's time water regulators took hold and made us do this.

"Local authorities don't want to lose charge of their water, because I don't care what anyone else says, we can supply our own water a hell of a lot cheaper than what of these big conglomerates can do."

Malcolm also acknowledges that not everyone would be happy with the decision.

"We're not the most popular council in town right now, or around at present for chlorinating our water but I totally understand where the people of Kawerau are coming from."