Irish Water says pesticide is still being detected in water supplies in Cork.
Pesticides have been detected in Glashaboy, Glanmire and Macroom public water supplies.
There is no immediate risk to health from the pesticide levels but the utility says it is vital that farmers and other users follow best practice when spraying their lands.
Irish Water points out that the legally permitted limit for pesticides in drinking water is set at a level equivalent to one drop in an Olympic-sized swimming pool.
The utility’s regional drinking water compliance specialist, Deirdre O’Loughlin, is urging farmers and other essential workers managing land to protect water sources.
Ms O’Loughlin says the herbicide, MCPA, used to kill rushes on a wetland, was one of the most commonly found.
MCPA accounted for 63% of the pesticide exceedances detected nationally in public water supplies last year but the utility also routinely tests for other pesticides.
While MCPA is the main offender, other pesticides such as 2,4-D, fluroxypyr and MCPP (also known as mecoprop) are being detected more frequently than in the previous year.
Ms O’Loughlin says 82% of drinking water supplies come from surface water sources such as rivers, lakes and streams.
“The Glashaboy, Glanmire and Macroom water supplies are all vulnerable to contamination from land and animal run-off,” she points out.
Careless storage, handling or improper application of any pesticide product can easily result in traces ending up in drinking water.
Efforts to reduce the incidence of detections are being coordinated by the National Pesticides and Drinking Water Action Group chaired by the Department of Agriculture, Food and the Marine.
Irish Water is working in partnership with members of the group that include other government departments and agencies, local authorities, industry and farming organisations.
Chair of the action group, Dr Aidan Moody, says pesticide users should also first consider if there are alternative non-chemical weed or pest control methods that can be used.
“If pesticides have to be applied users must make sure they are aware of and follow best practice measures to protect water quality,” he advises.
A video on the correct use of MCPA can be viewed on Irish Water’s YouTube channel at: https://youtu.be/xQqtZ7jifUs
Advice is also available on the Teagasc website.