Well water treatment in Co. Carlow

Private wells in Co. Carlow

The 2022 Census counted 5,362 Carlow households on a private well or other private source, 24.2% of the county and the third highest share in the State, covering 16,102 people. That's up from 4,958 homes in 2016. Group schemes are small here, 1,006 homes or 4.5%, so most homes off the public mains have their own supply. Public mains serve 69.3%.

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 Carlow well

The Geological Survey of Ireland (GSI) has no county groundwater report for Carlow, so this comes from its reports on the individual groundwater bodies, based on council and group scheme sources rather than household wells. Put simply, Carlow has two kinds of water.

Hard water in the Barrow valley

West Carlow, down the Barrow valley through Carlow town, Leighlinbridge and Bagenalstown, sits on a karst limestone aquifer with sand and gravel along the river. GSI sampling shows the gravel water to be very hard, and the limestone around Goresbridge, just across the border in Kilkenny, is expected to give hard water.

Soft water in the east and south

Around Tullow, Rathvilly and Hacketstown the rock is granite and slate, and EPA sampling shows soft, low-mineral groundwater. Across the wider area that takes in the Blackstairs and south Carlow, the limited GSI data show moderately soft water, 82 to 94 mg/L, with low alkalinity. A softener often isn't needed here. Soft, low-alkalinity water can be on the acidic side, though, so check the pH on your report: low pH eats copper pipe and leaves blue-green stains.

Iron and manganese on the north-west edge

The Castlecomer Plateau reaches into north-west Carlow, and in its sandstone the GSI found natural iron and manganese consistently above the EU limits. That means orange staining, black specks and filters that clog quickly.

Bacteria and nitrate

There are no Carlow figures for bacteria in wells, but the EPA estimated in 2016 that at least 30% of Ireland's private wells are contaminated by E. coli. On nitrate, the EPA's report for 2020 to 2023 found that most of the groundwater monitoring points averaging over 25 mg/L of nitrate are in the south east and along the southern coast, mainly from intensive farming, and Carlow is one of the counties where the Nitrates Action Programme requires shallow cultivation or a sown crop after harvest on tillage ground. If you're beside tilled ground, ask the lab for nitrate. See our guides to bacteria and nitrates.

What we usually fit in Carlow

Which stages you need depends on which side of the county you're on. The usual line, in this order:

1. Sediment filter to protect everything after it.
2. pH correction, mainly in the east and south, if the report shows low pH.
3. Iron and manganese filter if the report shows them, most likely toward the Castlecomer Plateau.
4. Water softener in the Barrow valley. On the soft granite water to the east 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. Carlow instead.

The well grant in Carlow

Carlow County Council's Environment Section runs the well grant (059 9136231, wellgrants@carlowcoco.ie). The application form, guide, terms and the claim form 1b are all on its well grant page. 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.