Well water treatment in Co. Kilkenny

Private wells in Co. Kilkenny

The 2022 Census counted 9,941 Kilkenny households on a private well or other private source, 27.1% of the county and the second highest share in the State, covering 30,984 people. That's up from 9,090 homes in 2016. Another 3,127 homes are on a group water scheme, and 63.1% are on public mains.

A household well is exempt from the drinking water regulations, so testing and treating it is down to the owner. The EPA advises a test at least once a year.

What's usually in a Kilkenny well

Kilkenny has three kinds of ground and the water follows them. The Geological Survey of Ireland (GSI) figures below come from larger public and group supplies, not household wells.

Hard water on the limestone

Limestone underlies the Central Lowlands from Goresbridge to Callan, and the water there is hard to very hard. Paulstown measured 292 to 377 mg/L, and Urlingford, Bennettsbridge and Callan over 350. The south is much softer: Glenmore measured 91 to 144 mg/L and Piltown 53.

Iron, manganese and rotten-egg smells

The Castlecomer Plateau and Slieveardagh Hills, about 21% of the county, are sandstone, shale and old coal measures. The water there is moderately hard to soft, with frequent iron and manganese problems, and in the Castlecomer sandstone both consistently exceed the EU limit. Hydrogen sulphide, the rotten-egg smell, is linked to the shaley limestones. See iron in well water.

Acidic water in the south

The GSI warns that low pH and corrosion problems can occur where the older rocks in the south of the county have thin or peaty soil over them. Near Belview the volcanic rock gave slightly acidic water, around pH 6.6, with iron and manganese above the limit in the raw water. Acidic water eats copper pipe and leaves blue-green stains.

Bacteria

Of 39 larger supplies, 80% had E. coli or faecal coliforms in at least one raw water sample. The GSI says farmyard dirty water and poorly sited or built septic tanks are a significant influence on groundwater across the county. In 2024 the EPA's map of private group schemes failing the E. coli standard included Barna-Kilrush and Dunbell No.2 in Kilkenny, and that October the council issued boil water notices, on HSE advice, for the Dunbell scheme and the Barna Kilrush scheme at Freshford. Those are group schemes, not household wells. See bacteria in well water.

Nitrate

The GSI calls raised nitrate relatively widespread in Kilkenny: 23% of supplies went over 50 mg/L at least once, and 56% were over 25 mg/L two or more times. More in our nitrates guide.

What we usually fit in Kilkenny

What goes in depends on which part of the county you're in. The usual line, in this order:

1. Sediment filter to protect everything after it.
2. pH correction, mainly in the south, if the report shows acidic water.
3. Iron and manganese filter, common on the Castlecomer Plateau, which takes the rotten-egg smell too.
4. Water softener on the limestone of the Central Lowlands. In the soft south it often isn't needed.
5. UV disinfection if the report shows E. coli or coliforms, fitted last on the main line.
6. Reverse osmosis at the kitchen tap, which also takes out nitrate.

On mains water and only bothered by limescale? See our water softener page for Co. Kilkenny instead.

The well grant in Kilkenny

Kilkenny County Council's Rural Water section handles the well grant, at County Hall, John Street, Kilkenny ((056) 779 4076, ruralwater@kilkennycoco.ie). Ask them for the application and explanatory booklet before you start. A house connected to Uisce Éireann or a group water scheme doesn't qualify, and nor does one that has had a water supply grant in the past seven years. Bring the council your lab report and our itemised quote. Our guide to the private well grant covers the rest.