The Department of Social Protection has confirmed it will not require proof that an Irish Water bill has been paid before handing over the money.

That’s despite the fact the grant was introduced by the Government to help households with their bills in a move aimed at quelling growing public protest over water charges late last year.

With the grant, the flat rate bill for a single person household will be reduced to €60 and €160 per year for a multi-occupancy household.

Every household is entitled to the €100 once they register with Irish Water, including those who are not Irish Water customers because they are on group water schemes or have wells and septic tanks.

But because these households won’t have to pay bills, the requirement that any household produce proof of bill payment when applying for their €100 has been omitted from the legislation.

Irish Water said it was a matter for the Department of Social Welfare to oversee the grant scheme. The department said the legislation was a matter for the Department of the Environment.

A Department of Social Protection spokeswoman said details required for the grant were a PPS number, confirmation registration with Irish Water, proof that the house claimed for was the primary dwelling, and details to enable payment. She confirmed the law does not insist bills are paid before the grants are paid out.

The first grants are due to be paid in September and each year after that up to and including 2018 at a cost of €130m per annum.

The loophole emerged after another testing day for Irish Water following Environmental Protection Agency findings that 121 of the country’s public drinking water schemes are at serious risk of contamination.

Jerry Grant, head of asset management at Irish Water, said the number would be reduced to 100 by the end of this year. He added that bringing all supplies up to standard would require investment of €2.3bn over the next six years — much of which would have to be borrowed.

That sum includes around €500m that will have to be spent removing lead pipes from the public network and treating supplies in homes where internal lead pipes remain.

Mr Grant said Irish Water’s ability to borrow would be determined by its income stream but he could not give details on how the company intended pursuing customers who did not pay their bills.

“We believe people will pay and if we deliver the improved services, that will help to get us over the line,” he said.

So far, 60% of households have registered with Irish Water, with the rest facing a February 2 deadline. Mr Grant said those who do not register by then risk being billed the higher flat rate charge of €260 when the first bills are sent out in April.