Londonderry County Borough Water Hardness & Quality Report (2026)

Northern Ireland Water is the utility that supplies Londonderry County Borough, also known as Derry City, with water. The primary source for this region is the River Faughan, a surface water supply abstracted near Eglinton in County Derry/Londonderry. This river catchment serves about 35,000 people, with a daily capacity of 40 million litres. Treatment involves screening, filtration, and chemical processes at a facility near the river. Ongoing improvement works, including projects like Faughan Wet Woods, are underway to protect the supply for the future.

The geology of the Faughan valley includes upland areas covered in glacial till, which lies atop Carboniferous limestone and Dalradian schists. Peaty moorlands also contribute to the surface runoff in this watershed. These geological formations, particularly the siliceous schists and the acidic nature of the peat-influenced flow, result in very soft water. Unlike harder supplies drawn from groundwater in calcareous areas, this surface water picks up minimal minerals.

Because the water is very soft, homeowners in Londonderry County Borough will notice that scale buildup is minimal, which is good news for appliances like kettles, boilers, and washing machines. Soap and detergents also lather easily, meaning you might use less. You won't need a water softener, and indeed, one isn't recommended due to potential risks like sodium addition or increased corrosion. Routine descaling is rarely necessary; the focus should be on general cleaning. NI Water manages water quality and provides contact information for specific analysis if you have specific concerns about lead, copper, or other contaminants.