Household water quality

Drinking water comes from two different sources in Ireland: lakes, rivers and streams (surface water); and springs and boreholes (groundwater). Surface water will almost certainly have to be treated to make it safe to drink, while groundwater may have to be treated depending on the quality of its source.

Water treatment doesn't just mean adding fluoride, although of course this helps. Initially, coagulation removes dirt and other particles suspended in water. Subsequently, heavy particles sink to the bottom during sedimentation, before the finer parts are filtered during the filtration stage. Finally, disinfection in the latter stages kills any remaining bacteria.  

Several factors can affect the quality of drinking water before it even reaches the treatment stage. If there is high rainfall, for example, extra organic material may be washed into rivers and streams. Conversely, if rainfall is low, these sources can dry up altogether. Other factors affecting water sources include the type of soil and bedrock characteristics, and agricultural practices where slurry and excess fertiliser may enter surface and groundwater systems.

Different factors tend to affect the treated drinking water. These include breakdown in the treatment process; lack of disinfection and filtration; problems with equipment; power outages or dirt in distribution pipes. Sometimes, poor quality is simply due to the water being drawn from an unsuitable source.

Since 1 January 2014, responsibility for public water supplies has transferred from local authorities to Irish Water, the new national water services authority. Under the new system, local authorities operate public water supplies on behalf of Irish Water.

Drinking Water Quality

Nationally, the Drinking Water Report for Public Water Supplies 2019 shows that the quality of drinking water in public supplies is high, with microbiological compliance better than 99.9% and chemical compliance at 99.6%. Despite these achievements however, a number of concerns remain at a national level, including:

• High levels of disinfection by-products in water supplies
• Persistent pesticide failures in some supplies
• Large numbers of lead pipe connections in properties
• An increase in detections of the parasite Cryptosporidium

You can check the current quality of your drinking water supplies on the Irish Water website here.