More than 4700 people in Havelock North have been infected by gastric illness linked to campylobacter in the town's water supply, the latest household telephone survey shows.

That is about one third of the 14,000 residents of the Hawke's Bay town.

Seven people with confirmed cases of campylobacter remain in Hawke's Bay Hospital, one fewer than yesterday.

The Hawke's Bay District Health Board said the number of people visiting their GP was continuing to fall, and there had been no evidence of a resurgence of cases.

Interim tests have found the bacteria was most likely to have come from ruminants such as cattle, sheep or deer.

The Hawke's Bay Regional Council said it could still not give a timeframe for determining what caused the contamination of the water supply.

The council's resource management group manager, Iain Maxwell, said the council did not believe the Tukituki River was to blame, but it could not be completely ruled out.

"I can't offer you an absolute, definitive 'we will know by this date, at this time', all I can tell you is that we are sharing information with the right authorities, as we learn it."

Meanwhile, further tests of a private bore that supplies Haumoana School have confirmed that there is no E coli present.

Public meetings in Havelock North

Public meetings on the water contamination in Havelock North will be held next week in the town.

The Hastings District Council said it would give an update on how it was fixing the water supply and the investigation into the contamination, and answer questions,

Two meetings will be held in the Riverbend Bible Church at 5.30pm on Tuesday 30 and Wednesday 31 August.

For those unable to attend, a live streaming on the internet would also be set up: Visit Riverbend Bible Church's website then click on Live Stream.