The number of water supplies under investigation for failure to meet pesticide standards has fallen by 20%, according to the latest figures from the Environmental Protection Agency (EPA).

At the end of 2018, there were 42 supplies serving almost 283,500 people under investigation by the EPA.

This was down from 53 supplies affecting 660,000 people at the end of 2017.

The limit for pesticides in drinking water is 0.1 micrograms per litre

The figures were published in the EPA’s 2018 drinking water report for public supplies.

In 2018, three-quarters of the failures detected were of the herbicide MCPA, which is used for rush control in grassland.

The limit for pesticides in drinking water is 0.1 micrograms per litre, which is considerably lower than levels that would impact on people’s health.


In 2016, Irish Water began a standardised pesticide monitoring programme for 21 pesticides.

Of the 42 supplies being investigated, 34 had failures during 2018, while seven failed in 2017, but there were not enough samples taken to confirm the issue was resolved.

Persistent failures

There were persistent failures identified in three of the supplies being investigated.

These were Cavan rural water supply; Belturbet, Co Cavan; and Clonroche, Co Wexford.

A further four supplies with persistent failures are under investigation from 2017.

The other 35 supplies had either once-off failures or non-persistent failures.

Irish Water carried out increased sampling in these supplies to investigate the extent of the problem or to confirm whether the issue was resolved.

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