Well water treatment in Co. Cork

Private wells in Co. Cork

Outside the city, Cork leans heavily on private water. In the Cork County Council area the 2022 Census counted 34,072 households on a private well or other private supply, 26.7% of homes. Group schemes serve far fewer, 4,998. In some districts it's close to half: 50.6% of homes in the Macroom area and 43.6% around Bantry, then 38.7% around Bandon and Kinsale, 30.1% around Skibbereen and 22.8% around Kanturk. In the city it's 1.0%.

Nobody monitors a household well for you. It's classed as an exempted supply, so testing and treating it is down to the owner. Every system we fit in Cork starts with a lab report.

What's usually in a Cork well

Iron and manganese

In its groundwater report for south Cork, the Geological Survey of Ireland (GSI) lists high iron and manganese among the main problems. It's mostly natural, from peat, muddy limestones, the Old Red Sandstone and the Cork Group rocks, and in West Cork small domestic wells pumped at low rates tend to show it. You see it as orange or brown staining, black specks and an off taste.

Bacteria

In the GSI's raw-water sampling, 8 of 25 public groundwater supplies contained faecal bacteria. It says that in certain areas more than half of private wells are likely to be polluted at least some of the time, by septic tanks or farmyard waste. In the karst limestone of North and East Cork, microbial pollution can travel very quickly from the surface into the groundwater. See bacteria in well water.

Nitrate

The same report calls high nitrate the most important groundwater issue, found in many public supplies and some private ones, at sources including Minane Bridge, Stoneview near Blarney, Aghabullogue, Coachford, Ballinspittle and Killeagh. The EPA also puts most of its groundwater sites with nitrate above 25 mg/L in catchments draining the south east and south west. See nitrates in well water.

Hard in the valleys, softer in the west

The limestone valleys from Buttevant to Mitchelstown and Mallow to Fermoy, and the limestone around Midleton, give hard water, 200 to over 400 mg/L. Around Charleville the GSI measured 280 to 360 mg/L and says hydrogen sulphide, the rotten-egg smell, may be problematic. On the sandstone and Cork Group rocks of West Cork and around Kinsale the water is softer, 43 to 224 mg/L, and can be acidic: a source at Upton recorded a pH of 5.8 to 5.9.

What we usually fit in Cork

Hard water in the limestone valleys usually takes the full line. Softer West Cork water starts with pH correction and iron removal, and a softener is often not needed. In treatment order, with stages left out if the report doesn't call for them:

1. Sediment filter to protect everything after it.
2. pH correction where the report shows acidic water, as it can on the sandstone in the west.
3. Iron and manganese filter, which also takes the rotten-egg smell.
4. Water softener in the limestone valleys, after the iron filter so it doesn't foul.
5. UV disinfection if the report shows E. coli or coliforms, fitted last on the main line so the water reaching the lamp is clear.
6. Reverse osmosis at the kitchen tap, which reduces nitrate in your drinking water.

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

The well grant in Cork

Cork County Council runs the individual domestic well grant, with an online application (wellgrants@corkcoco.ie, 021 4285929). Works done before the council has inspected and approved them don't qualify, so apply first and fit second. Bring the council your lab report and our itemised quote. We'll tell you which tests to ask the lab for: iron, manganese, hardness, pH, nitrate, E. coli and coliforms at the very least.