Dwayne and Hedley Edwards are fed up with the lack of help from local councils to remove a rotting cow carcass from their water supply.

A cow carcass left to rot and seep into the main water supply of a Waikato school has sparked health concerns.

One woman who became ill after the cow was shot is blaming contaminated water.

The cow was shot by its owner around three weeks ago. The carcass was left in a paddock through which three natural springs flow.

SUPPLIED The dead cow has been rotting into the family's waterway for three weeks.

The springs feed into bores that supply the Edwards family and Ruawaro School, which has closed off its intake until the water can be tested and deemed safe. The water eventually runs into Lake Whangape.

The Edwards family raised concerns with the Waikato District Health Board and two councils after Jan Edwards started feeling seriously unwell.

"It might be a coincidence, but it seems funny that three weeks ago, [the neighbour] kills a cow and leaves it there and a week later I get sick."

"It's putrid," said her son Hedley, who found the decomposing cow in their neighbour's paddock on Tuesday.

"It's got maggots coming out from everywhere - it's got green bile spilling out of its guts."

The owner of the dead cow is out of the country and his son, Phil Darby, said he knew nothing about the carcass.

Hedley said his mother had been sick for the past two weeks, but the hospital couldn't figure out what was wrong.

"Now they're testing for all these high fandangle bugs, because no one can figure out what it is."

He then had the thought that it could be contaminated water from the cow.

Despite alerting the health board and Waikato Regional and District councils, the Edwards felt no one had really been able to help them.

"So who do you ring?" Dwayne Edwards wants to know.

While Jan Edwards was sick, her main concern was for the children at the school and her 16-month-old grandson.

In a statement, Waikato Regional council spokesman Derek Hartley said said the owner of the dead cow had been contacted and the carcass has since been removed.

And while there are penalties for not disposing of dead stock lawfully, "generally, we aim to ensure that landowners are aware of their responsibilities and to work with them to sort things out".

District Council spokeswoman Erin Rangi-Watt said staff had the authority to request a carcass removal, "and in extreme circumstances, we would remove it ourselves".

The Ministry of Education investigated and found the dead cow 200 metres from the school's bore.

"Because of the location of the cow's carcass some distance from the site of the bore, there isn't any immediate reason to think it may have contaminated the water supply," spokeswoman Katrina Casey said.

The water was last tested two weeks ago and that test was clear. The school is now now awaiting results of a test taken on Thursday. Its bore water intake would remain closed off until then.

Dr Anita Bell, medical officer of health for the Waikato District Health Board. said the water should not pose a risk as long as it is treated.

If it's not treated, she said there is always a risk, especially of gastroenteritis disease.

The Edwards family do not treat their water, but have it tested every year and it's always been safe to drink.