Cootehill water supply Do Not Consume notice is affecting over 2,000 people in Cootehill.
Irish Water has issued the notice due to elevated levels of manganese in the supply.
The utility says the notice was issued after consultation with the HSE.
The Cootehill Public Water Supply Scheme supplies 2,190 customers.
They're being told not to consume their water and instead use alternative supplies.
Irish Water says this is not a boil water notice and boiling water will not make it suitable for consumption.
Water tankers will be placed at the Darley National School and the White Horse Hotel. However, people must bring their own containers. This water must be boiled before it is consumed.