Welsh Water (Dŵr Cymru) Tap Water Quality

Welsh Water (Dŵr Cymru) supplies Wales & Herefordshire with drinking water drawn from upland reservoirs across Wales including Llyn Brianne, Llyn Celyn, Llandegfedd, Cantref, and Claerwen.

Welsh Water draws from some of the highest rainfall catchments in the UK. Welsh upland reservoirs receive annual rainfall of 1,500–2,500mm, producing naturally soft, low-mineral water throughout most of Wales. Cardiff and Newport typically see hardness of 60–90 mg/L; Swansea and the west are even softer at 30–60 mg/L. Herefordshire zones, supplied from the River Wye catchment, can be slightly harder. Colour from peat-influenced upland sources is periodically elevated. Welsh Water serves a geographically extensive but sparsely populated rural area, meaning some zones have long distribution networks that require careful chlorine management.

Typical water profile

With typical hardness of approximately 75 mg/L CaCO₃, water in the Welsh Water (Dŵr Cymru) supply area is classified as soft. This means minimal limescale risk and good appliance longevity across the supply area.

Notable: Soft water across Wales and Herefordshire. Low limescale risk. Some elevated colour from upland sources. Active PFAS improvement programme under DWI enforcement.

Is Welsh Water (Dŵr Cymru) water safe to drink?

Yes. All treated water supplied by Welsh Water (Dŵr Cymru) meets the UK Drinking Water Regulations. The Drinking Water Inspectorate (DWI) audits every water company annually — Welsh Water (Dŵr Cymru) serves 3 million customers across 69 supply zones. Each zone is tested thousands of times per year and results are published in the annual compliance report.

However, water quality varies significantly between zones within the Welsh Water (Dŵr Cymru) supply area. Your specific zone may have different hardness, nitrate, or THM levels from your neighbour in a different zone. That's why it's worth checking your exact postcode above.

How to check your Welsh Water (Dŵr Cymru) zone

Enter your postcode in the box above to see zone-specific data for your address — including hardness, nitrates, lead, chlorine, fluoride, and THMs — drawn directly from Welsh Water (Dŵr Cymru)'s most recent annual compliance report.