An investigation into a previous contamination in Havelock North's water supply has found earthworks on a neighbouring mushroom farm may be to blame.

Hastings District Council released a report on the contamination today, as a new gastro crisis makes more than 3000 people sick.

This morning, a tanker providing Havelock North with clean water from Hastings tested positive for bacteria, pushing the council to chlorinate both towns' supplies.

Mayor Lawrence Yule today said he had just received a report about a similar contamination last year and would release it in a bid for transparency.


In October last year, E. coli was found in a well at the Brookvale borefield, which draws water from the Te Mata aquifer, providing all of Havelock North's water.

The bore is about 200m from the two bores at the centre of the current outbreak. It has been shut since.

At the time, the water was chlorinated for several days, and no one fell ill. A council investigation into the cause of the contamination could not pinpoint where the bacteria came from.

However, the report, by consultants Tonkin and Taylor, said it may have come from the neighbouring Te Mata Mushrooms.

The farm had done earthworks last year, which may have "compromised" the aquifer, the report said.

The report said wastewater from the mushroom farm, which may contain bacteria, could have become "hydraulically connected" to the groundwater system.

The report recommended the council assess whether the changes to the landscape could adversely affect groundwater, and that it do a "human health risk assessment".

It further recommended an expanded testing programme to better identify the source of contamination in the Brookfield borefield.


Te Mata Mushrooms owner Michael Whittaker said he was yet to read the full report.

"I am not qualified or make speculation on that - I don't know how it works, so I simply don't know," he said.