UPDATED 4.06PM: It's a case of one down, two to go for the water supply of Pahiatua.

The latest water test is clear of E coli and Tararua District Council has said it will withdraw a precautionary boil-water notice when it has three clear tests.

The council issued the notice on Friday and began chlorinating the water, saying tests showed E coli in the water supply of the lower North Island township.

Mayor Roly Ellis said "It'll take a bit to flush the whole system because obviously the old water is still in the system," he said.

In the meantime, locals are being told to keep boiling water for drinking, food preparation, brushing teeth, and preparing infant formula.

Newstalk ZB reporter Georgia Nelson, who is in the town, said locals have told her they've had enough.

She said a steady stream of people have been coming and going from the fresh water tanker in the middle of town all morning, including Joanne Smith, who visits every few hours to pick up fresh water for her calves.

Smith said her calf troughs are on the town water supply, and she's had four die already and many others are sick.

"The ones that you seem to get well, and you think that the runs are starting to sort of firm up a bit, and you just turn up and they're dead. So, I'm quite over it."

Meanwhile, the boil water notice in Havelock North has been lifted after 5000 people fell ill with the effects of water contamination.

In a statement, the Hastings District Council said the third clear water test in a row has come back today, meaning water no longer needs to be boiled.

Residents, building owners, business owners and their staff are being asked to take steps to ensure pipes are flushed through before drinking the water.