The Irish Water Board has said it will take two-and-a-half to three years to fully install water meters in all qualifying properties.
Earlier this year Minister for the Environment Phil Hogan said that work would be completed by the end of 2014.
The Irish Water Board says it is going to the market for boundary box and meter procurement in the next few weeks.
However a survey of every water mains in the country must be carried out and that process will begin in October.
Irish Water Board Chief Executive John Mullins said survey and boundary box and meter installation will be carried out in parallel, region-by-region.
He said 1,000 people would be involved in the installation operation.
Mr Mullins said he did not know what the flat rate would be, as it was a matter for the Energy Regulator.
However, he said based on international charges, consumers could be looking at anything between €100 and €400.
Meanwhile, Minister for Communications, Energy and Natural Resources Pat Rabbitte has scotched reports that a flat water charge is to be introduced in place of water meters.
Mr Rabbitte said no Government decision had been taken on the implementation of a flat charge.