Irish Water has acknowledged figures on one of the two types of meters it has installed across the State cannot be read by householders.

Information on Irish Water’s website depicts meters showing a clear series of numbers, five against a black background, and the last three against a red background.

The black numbers represent water flow in denominations of thousands of litres; the red units represent hundreds of litres, tens of litres and litres.

Irish Water said both types of meters complied with required standards including the EU measuring instruments directive and were widely used internationally.

But it said “a low power radio unit” – which allows meters to be read remotely by a passing Irish Water van – partially obscures the red digits on one of the meter types.

The issue arose when residents in Beaufort Downs, Rathfarnham, in south county Dublin discovered they were unable to see all or part of the last three rows of red numerals.

Householder Alan Sullivan said residents could only view their water consumption in thousands of litres. They could not, for example, judge the consumption of a dishwasher, or an individual bath or shower – or even accurately assess if they had a leak on their property.

“A leak would have to show more than 999 litres overnight before we would be able to detect it,” he said.

Irish Water said: “Customers should be able to see at least two red digits, which gives the usage in cubic meters to two decimal places or to the nearest 10 litres. If the reader has no red dials on the meter they should contact us”.