Mayfield's water is set to be sourced from stock water supplies if the bore dries out.

Residents of a small town in Mid Canterbury are outraged at plans for the town's water supply to be sourced from stock water.

Mayfield's water supply is running low following three consecutive winters of low rainfall and the Ashburton District Council is concerned the bore will run dry in the next few weeks.

Mayfield has been placed under water restrictions and the council has also hired a portable treatment plant that will allow it to use a stock water race if required.

In a letter to residents, the council described the bore water level as being "extremely low (less than one metre)".

READ MORE:

*Ashburton water bottling plant up in the air

*For sale: 40 billion litres of Canterbury's purest water

"To ensure Mayfield has a continued supply of safe, clean drinking water, council will be switching the water supply from the bore to a water race," said council water engineer Matthew Glennon in the letter.

"A mobile water treatment plant will be installed which will clean and treat the stock water to make it safe and clean."

The Mayfield bore was put in by residents as an alternative to a previous river stock water system in 2009.

Ashburton's deputy mayor Neil Brown said the well provided quality water, just not the quantity to be reliable source.

"There is no date for the treatment to start, they are just putting plans in place that if the well gives up altogether they can switch to the water race system," Brown said.

"It is like having an emergency generator for if the power goes off."

The water treatment plan is just "forward planning" until the council can come up with a permanent solution, Brown said.

Despite assurances, residents are not impressed.

Mayfield's Deb Manhire is concerned that the "interim measure had no time frame" and that the community had no consultation on the process until they received a letter informing them of the plan last week.

"In this country that has the clean green image for tourism, that people are reduced to drinking treated stock water does not paint a pretty picture," Manhire said.

"I don't care if it is clean and safe to drink scientifically, it's an affront to human dignity.

"The rest of the district is getting the good pure artesian water while we are left drinking treated stock water is just unfair and discrimination."

The council came under fire earlier this year for the proposed sale of the right to extract 40 billion litres of pure, artesian water to a bottled water supplier.

"The council is going to vote again in February on whether to sell off our pure water while their rate-paying residents are treated as second class citizens drinking stock water," Manhire said.

The council is also keeping an eye on bores supplying Mt Somers and Montalto in case they needed to be switched to water races as well.

Campaign group Bung the Bore Bung spokeswoman Jen Branje released a statement condemning the action.

"There is a psychological impact to communities that are reduced to drinking second-hand water," Branje said.

"The Ashburton District Council believe there is a major 'leak' in the Mayfield water system.

"In fact, they went so far as to put meters in place to try and find that leak. They have known since 2013 that Mayfield's water source was in big trouble, but did nothing about it.

"In summer, domestic users all over Mid Canterbury are put onto restrictions, while irrigators continue to pour water to ground for private profit."