Monaghan County Council has issued a "do not consume notice" for all customers supplied by Three Mile House & Togan Public Water Supply Scheme.
Following consultation with the HSE Irish Water, the do not consume notice was issued due to elevated levels of manganese.
The notice applies to approximately 319 customers.
Tankered water will be in place at the Community Centre in Three Mile House from this evening to provide an alternative water supply to customers.
Customers are reminded to use their own containers when taking water from the tanker and to boil water before consumption as a precautionary measure.
In a statement to Northern Sound, Irish Water drinking water compliance and operational experts said they are "working" with colleagues in Monaghan County Council to resolve this situation as soon as possible.
