It follows a warning from the Environmental Protection Agency that if the council does not address persistent exceedence of trihalomethane or THMs in the supply, it will be prosecuted.
THMs are organic chemical compounds which can react with chlorine in the supply.
Dervla Devenney, the EPA's Inspector in Donegal says while there are claims that THMs may cause cancer, there is no hard evidence to back that up.
However. she says the EPA, the HSE and the council are taking this issue seriously..........