The head of the government's inquiry panel has laid the blame for the Havelock North water contamination crisis squarely at the feet of two councils.

Panel chair Lyn Stevens QC has delivered stage one of the report into what caused, and who is to blame for more than 5,000 people becoming sick with campylobacter last August.

Mr Stevens says the outbreak was most likely caused by heavy rain washing sheep faeces into a nearby stream, which then flowed into the aquifer which supplied the contaminated Havelock North bores.

He says the Hawke's Bay Regional Council was meant to ensure the aquifer was secure.

"Protection of the water source - in this case the aquifer - was the first and critical step to ensuring safe drinking water."

Lyn Stevens said the Hastings District Council also put the public's safety at risk.

"The District Council did not manage the maintenance of plant equipment or keep records of that work."

The full report of the inquiry panel can be found on the Department of Internal Affairs website.