Can you beat the cap? Under the new water charges regime, Minister for the Environment Alan Kelly has encouraged householders to save money by using less water.

Charges will be capped at €60 for a single-adult household and €160 for all others who register with Irish Water.

But Mr Kelly says households with water meters will be able to pay even less by using less water.

“We estimate that if metered households can reduce their water consumption by between 10 and 15 per cent, then approximately half of Irish households will be able to ‘beat the cap’ and have bills lower than the amounts outlined,” he said.

In reality, however, water experts say householders would have to resort to major conservation measures to save any money.

Under the new regime, the cost per 1,000 litres of water will be €3.70.

A typical family of four, for example, uses about 150,000 litres of water a year.

To accumulate charges of less than the capped rate, the average family’s water use would need to be less than 85,000 litres – a drop of about 45 per cent on normal use.

These figures include free allowances for each child, worth 21,000 litres each.

Five toilet flushes

On a daily basis, this means a family of four would need to use fewer than 235 litres. This is equivalent to no more than two quick showers, five toilet flushes, a single load of a washing machine and one use of a dishwasher every day.

There is no scope in these usage figures for a bath or shower for the two children, or for water used in cooking or drinking.

A single-person household would be even more limited, if they are to beat the capped charges.

Experts agree that a typical single adult uses about 50,000 litres of water a year.

To beat the €60 cap, this would require using no more than about 16,000 litres of water a year, a reduction of almost 70 per cent on normal use.

This is equivalent to about 44 litres a day. or a single shower, a single toilet flush and one cup of tea every day.

Unrealistic figures

Water experts say that, in practice, many of these figures are unrealistic and raise questions over why €500 million has been spent on installing water meters across the State.

According to research carried out on behalf of Irish Water earlier this year, more than 80 per cent of people misjudge how much water they use on a daily basis.

Opposition political parties are also sceptical that anyone will be able to accumulate savings under the capped rate.

Cllr Malcolm Noonan, the Green Party's environment spokesman, said: "The real outcome will be that those who want to keep wasting can do so, and those who invest in water efficiency or reduce their consumption will see no benefit."

He added: “From day one, the Government told us that the creation of Irish Water was not a revenue-generating exercise, and that the principal concern was incentivising water conservation. We see now that that was a lie.”

Mr Kelly, however, has insisted that some people using metres will be able to get their bills below €100.

Not only that, but he says when the €100 allowance for registering with Irish Water is factored in, they “will likely be slightly better-off because of the introduction of water charges and meters”.