Brown, silty water coming out of Napier taps is the result of sediment being stirred up by maintenance work on old pipes, and a chemical reaction caused by introduction of chlorine, a water expert says.
Napier City Council has apologised after hundreds of residents in the suburbs of Onekawa, Tamatea, Greenmeadows and Pirimai had discoloured, at times black, water running from their taps over the weekend.
It's not the first time it's happened in Napier, but the council says the latest incident occurred after water mains were cleaned on Sunday, which ended up affecting a much wider area than anticipated.
Some residents took to social media over the weekend to vent their frustration, and post photos of the dirty water coming out of their taps.
Napier City Council received 125 complaints in the week to Sunday about water quality, it said.
It later apologised to affected residents on its Facebook page.
"Apologies for the water discoloration problems that you may have experienced over the weekend, as a result of the scheduled water mains cleaning.
"In some instances the affected areas were wider than anticipated. If you are still experiencing discoloured water, please run your outside taps on full for 20 minutes - and it would be great if you can direct this water into gardens, so it won't go to waste," it said.
Anyone still experiencing issues should contact the council, the post said.
The Council said the water is perfectly safe to drink.
"As much as it doesn't look great, yes it is safe. The water has been tested and there's no harmful bacteria in the water," chief executive Wayne Jack said.
The work over the weekend to install a new booster pump disloged sediment in old pipes, and while that should have settled down longer-term solutions to stop it happening again will take time, he said.
The council would also look at bringing forward work to improve the city's water network, he said.
Napier resident Hannah Buckley said the issue had been going on since March, when the councils started chlorinating all public supplies.
The water in her bath ran black at the weekend after the council flushed drains, she said.
Aqua Filter Hawke's Bay owner Brian Cawood said the brown water was the result of work being done to upgrade old infrastructure and the introduction of chlorine to the water supply.
The maintenance stirred up sediment in the old pipes that had "been there for 100 years" while chlorine reacted with iron and maganese in the water, creating a brown colour.
"You've got a situation where council is caught between a rock and a hard place. They are not in a position not to chlorinate because there's a liability issue there," he said.
"It's a not a quick fix. It needs a period of time to put other measures in place and we are working as quickly as we can to do that."
All public water supplies in Hastings and Napier have been chlorinated since March this year, after the Havelock North water crisis in 2016 [caused 5000 people https://www.radionz.co.nz/news/national/345570/new-zealand-s-drinking-water-a-mess to become ill with camplyobacter.]
Mr Cawood said he saw a jump in inquiries for water filters but with prices starting from $200 for a basic drinking water filter to more than $10,000 for a sophisticated whole-of-house filter, not everyone could afford to install one.
An online petition calling for the council to sort out the issue once and for all has gathered more than 700 signatures since Sunday.