Now, as the drought drags on through winter, residents outside of the remote NSW town are being forced to sign a document stating they won't sue authorities if the drinking water delivered to their homes makes them sick.

Rob McBride and his family live on the sheep property Tolarno Station on the banks of the Darling River some 50 kilometres south of Menindee.

For years the family sourced their drinking water from the river and rainwater tanks, but now they are reliant on water delivered by charities, or they buy potable water from the local council.

Central Darling Shire Council will only deliver water to Tolarno Station, however, if the McBrides sign a document guaranteeing they won't sue the council or the state government if they become sick.

"It's blackmail and you can't do that," Mr Mcbride told AAP.

"If you don't sign that paperwork then you don't get any water supplied to your house and your family. We've got a gun to our head."

Mr McBride is worried blue-green algae in the town's main water sources could be linked to the "soul-destroying" motor neurone disease.

Menindee's town water, and the water delivered to nearby rural residents, is sourced by Essential Water from Lake Copi Hollow which at present has an amber alert for blue-green algae.

Central Darling Shire Council's website says its potable water is safe to drink.

The council is responsible for carting the water to the rural residents. It says those who supply the potable water are required to provide the NSW health department with regular samples to ensure it meets Australian guidelines.

Essential Water insists the water it supplies is treated and tested to ensure it complies.

But, according to Macquarie University neuroscientist Gilles Guillemin, some cyanotoxins - which are produced by blue-green algae - are so small they can't be filtered out.

Professor Guillemin has been working since 2012 on developing technology to help quantify the toxins and identify exactly what it is about in blue-green algae in the water that triggers MND.

"I wouldn't drink the water, if I go there (to Menindee), I would drink bottled water," he told AAP.

But council general manager Greg Hill says residents are only asked to sign the waiver because the potable water is delivered "into a tank we have no control over".

The tanks on most properties previously held raw or untreated water from sources like the Darling River, which means they could be contaminated, Mr Hill told AAP.

"For this reason council asks that waiver be signed as we have no control over the maintenance and the cleanness of the storage tanks," he said in a statement.

Retiree Dick Arnold lives "a stone's throw" from Menindee and was also required to sign a waiver before potable water was delivered to his home.

That was the case even though he recently received a brand new water tank paid for by the state government.

"We certainly don't drink it," he told AAP. Instead, the water is used for washing.

Mr Arnold says he's never been asked to sign such a document before.

"It does make you wonder what's in the water. You can't trust anyone these days."

Both Mr McBride and Mr Arnold are concerned the water may contain traces of blue-green algae blooms which are also present in the Darling River and were blamed for the catastrophic mass fish kills in December and January.

"MND is a soul-destroying, debilitative and murderous disease," Mr McBride said.

"And the government gives us a disclaimer which effectively relinquishes them of all responsibility for future generations."

Australian Associated Press