The cost of replacing old water pipes has risen sharply in recent years, prompting a review of the country’s ageing infrastructure.
A survey carried out by consultants RTS found that the cost of repairing existing pipes had risen by 3.5 per cent in just a year.
RTS said that was the highest rate of increase for a single year since it began collecting data in 2004.
The Irish Water and Power Authority said it had commissioned an audit of the costs of replacing water pipes and that the costs for each of the previous two years had been cut by about £3m.
In total, the cost to replace old water infrastructure has risen by 6.5% since 2004.
But it said that, despite the sharp rise in costs, the overall level of investment was at a level that could be sustained.
Water infrastructure spending has been rising steadily over the last 20 years.
At the end of June, the Irish Water Agency said that total water infrastructure spending had risen in real terms by about 0.5pc over the past five years.
It also forecast a 3.3pc rise in the overall cost of water infrastructure from 2020.
Overall, the water infrastructure sector has grown by 7.6pc since 2004 and has accounted for 14pc of total infrastructure spending.
While costs have risen, overall investment has remained steady at around 40pc.
The latest survey found that only about 40pc of the total infrastructure investment was made in the water industry.
That included new infrastructure such as water treatment plants, which account for almost 40pc, but also new infrastructure, such as a new generation of sewage treatment plants.