A campaign to highlight the impact pesticides can have on water supplies is due to be launched as "spraying season" gets under way.
It comes as several water supplies have been prioritised for action this year because of recurring pesticide exceedances.
These include Greenmount in Louth, Longford Central in Longford, and the Foynes/Shannon Estuary supply in Limerick.
Uisce Éireann and the National Pesticides and Drinking Water Action Group (NPDWAG) are urging all pesticide users to take extra care when spraying vegetation.
The water utility has said that while pesticide exceedances recorded in water supplies have reduced by more than 50% in the last nine years since the action group was established, there are still a small number continuing to occur.
New figures from Uisce Éireann show that last year, a total of 69 exceedances of the legal limits for pesticides were detected in 24 public water supplies.
The figures were drawn from over 45,000 analyses carried out around the country.
Uisce Éireann said the figures represent a very high overall rate of compliance.
The majority of breeches were linked to the commonly used herbicide substance MCPA, which accounted for 49 of the non-compliant findings.
MCPA is an active substance in many commonly used herbicide products to control thistle, dock and rush.
The pesticide levels detected through the monitoring do not pose a risk to health, but preventing pesticides from entering the water is the most effective way to protect drinking water quality.
Where exceedances are detected, Uisce Éireann works with the relevant authorities, including the Local Authority environment sections, the EPA and the Department of Agriculture, to investigate possible causes and to implement remedial actions.
There has been notable improvement elsewhere on the network following "targeted engagement, local collaboration and consistent best practice implementation".
For example, the Belturbet supply in Cavan, the Hacketstown water supply in Carlow and the Newcastle West supply in Limerick, all recorded strong improvements last year, in what Uisce Éireann described as a "clear turnaround compared to previous years".
Chair of the NPDWAG Dr Aidan Moody said while there has been strong progress, 2025 results show there are still some instances of pesticides entering water sources.
"Even very small quantities can affect drinking water quality," he said.
He acknowledged the commitment of the farming community, who he said had played a vital role in reducing exceedances in recent years.
"We ask all pesticide users to always carefully consider whether pesticide use is necessary and, where it is, to follow best practice in every instance. Every responsible choice — whether selecting an alternative control method where possible or avoiding pesticide use in unsuitable weather conditions such as when rain is forecast — helps safeguard drinking water across our communities," Dr Moody added.
Drinking Water Compliance Senior Manager with Uisce Éireann Dr Patrick O'Sullivan said: "While the vast majority show full compliance, we are still seeing preventable exceedances noted, within a small number of supplies.
"Local action is delivering real improvements, and we are encouraging all pesticide users to keep up this positive momentum as we enter the 2026 spraying season".
