The new Bord Gáis subsidiary — responsible for overseeing the introduction of a national water metering scheme — said it was impossible to know the extent of the problem until meters are installed.
The potential bill of several thousand euro which customers could face to repair leaking pipes is likely to lead to pressure on the Government to introduce some form of grant scheme to assist affected households.
It is estimated that the current national leakage rate is 41%, although Irish Water said it would have no idea what level of leakage occurred in pipes near homes until water meters are installed.
However, it plans to introduce a system which could alert households consuming excessive levels to the possibility they are suffering leaks.
Irish Water acknowledged its target of lowering the national leakage rate to 20% could take 15 years or more to achieve because of the antiquated nature of much of the country’s 25,000km network of water mains.
The Government has indicated households will face a flat rate charge for water from 2014 as just 15% of homes will be metered by that date.
However, Irish Water expects its water billing system will be ready for rollout from Jan 2014.
The Commission for Energy Regulation, which will set domestic water charges, is to hold extensive public consultation on the issue next year. It will also determine free allowance levels and whether landlords or tenants should be responsible for paying a water bill.
Addressing the Oireachtas environment committee yesterday, Bord Gáis CEO John Mullins indicated domestic customers will not have their water supply disconnected for the non- payment of bills. He also stressed householders will not face any up-front cost for the installation of meters, while billing will not commence before 2014.
He predicted domestic water consumption would fall by 10% following the introduction of metering.
A €450m programme for the installation of meters to 1.05m residences will begin shortly, although it is unlikely to be fully completed before late 2016 at the earliest.
It is anticipated that many households, including apartments, which cannot be metered, will be billed based on assessed usage rates from 2014 onwards.
Mr Mullins told the committee there was no strong evidence to support claims that up to 500,000 households will not be suitable for water meters.
Up to 2,000 temporary jobs will be created by the appointment of a panel of 200 local contractors to be hired by Irish Water to install meters and boundary boxes over the next two- and-a-half years.
About 400 permanent jobs will also be created at an Irish Water customer care centre with 100 of these due to be in place by May 2013. Some 4,000 local authority staff working in the provision of water service will remain council staff, but will operate under service legal agreements with Irish Water up to 2017 and beyond.
Committee chairman, Michael McCarthy said it was “a large ask” to charge citizens for water for the first time and Irish Water must ensure the service is “second to none”.