The Environmental Protection Agency has warned that more than 50 treatment plants supplying water to over one million customers are vulnerable to failure, posing a risk to public health.

Director General of the EPA Laura Burke has said the growing uncertainty in Irish Water's planning and delivery of critical improvements to water treatment plants is undermining confidence in the security of supply of safe drinking water and putting the public's health at risk.

She also said that while the quality of water in public supplies remains high, supplies to over one million people are vulnerable to failure.

The EPA is becoming increasingly frustrated with Irish Water over delays and shortcomings in addressing problems related to water supplies and infrastructure issues.

In its annual report on the quality of our public drinking water the EPA said it is seriously concerned at the delays in the completion of works.

It pointed out that at the end of 2018 all water supplies on its remedial action list had completion dates no later than 2021.

But by the end of last year however, completion dates had been pushed out beyond 2024, with Irish Water stating it cannot commit to any completion date for some supplies due to the funding required not being available before 2024.

The report found that the quality of drinking water in public supplies remains high with 99.9% compliance with bacterial limits and 99.6% compliance with chemical limits.

But it warns that increasing uncertainty in Irish Water's planning and delivery of critical improvements to water treatment plants is making supplies vulnerable to failure, posing a risk to the health of a large portion of the population.

The EPA is also very concerned that Irish Water will fail to meet its commitment to remove all lead piping in the public water network by 2026.

It said it could take 60 years to remove the lead at the rate Irish Water is now progressing.