There was 42% fewer pesticide exceedances in public drinking water supplies in Ireland in 2021, a decrease of 34 from 2020.
In 2021, there were 47 exceedances and in 2020, there were 81.
MCPA is still the most commonly detected pesticide in drinking water sources, according to Irish Water's results.
MCPA is present in many commonly used herbicide products, which farmers use to kill thistles, docks and rushes.
There are currently six priority areas of concern where Irish Water is seeing frequent pesticide exceedances from its monitoring programmes, which will be prioritised for further action in 2022.
Priority areas
Irish Water's advice is to leave areas unsprayed so that native flowering plant species can "grow and support a range of insects including bees and other vital pollinators".
"Farmers should also bear in mind that application of herbicides reduces sward species diversity and could negatively impact on payments in future agri-environmental schemes," Irish Water said.
Irish Water’s drinking water compliance lead John Leamy said: "While our consultation with the HSE has concluded that the levels we are detecting do not represent a threat to public health, they are still however undesirable in drinking water and it is therefore imperative that users of pesticides are mindful of best practice when using herbicides or pesticides and seek out alternatives.”
Adding to this, Dr Aidan Moody from the Department of Agriculture and chair of the National Pesticides and Drinking Water Action Group (NPDWAG) said that the significant decrease in the number of exceedances recorded last year shows the good results that can be obtained when we all work together to protect water sources.
"Users of pesticides must always consider alternatives in the first instance and if the application of pesticides is considered essential make sure that they follow best practice measures to protect water quality," he said.
If pesticides have to be used, the basic steps to reduce risks to drinking water sources and the environment are: