The roll-out of water meters is under way, with the first being installed in Co Kildare.
It is hoped to have over 1 million meters fitted by the end of 2016.
People will be given notice before a meter is installed.
Irish Water has said the installation should not cause more than a few hours' disruption to supply.
Households should expect their first water bill at the start of 2015.
Those who have not received a meter at that stage will be billed on their estimated usage.