The water where you live

Predominantly hard igneous and metamorphic rock, with peat cover in upland catchments. Very little dissolves, so the water stays soft.

Upland surface water and reservoirs, often with natural colour from peat requiring colour removal.

Ordovician and Silurian mudstones, sandstones and volcanic rock across most of Wales, with Carboniferous limestone in parts of the south east and north east.

Upland reservoirs and river abstraction in one of the wettest parts of Europe.

Basalt of the Antrim plateau and a mix of older rocks elsewhere.

Lough Neagh and upland reservoirs. Lough Neagh supplies around 40% of Northern Ireland’s drinking water.

London Basin chalk beneath the London Clay, plus Thames and Lee abstraction from a chalk-influenced catchment.

A mix of Thames and Lee river abstraction into bankside storage reservoirs, and chalk groundwater.

Chalk of the North and South Downs and the Chilterns. Carbonate dissolution produces very hard, alkaline water.

Predominantly chalk groundwater, with river abstraction from the Test, Itchen and Thames.

Chalk across much of Norfolk, Suffolk, Cambridgeshire and Hertfordshire.

Chalk groundwater and the Rutland and Grafham pumped-storage reservoirs. The driest region of the UK.

Granite on Dartmoor and Bodmin producing very soft water, against Jurassic and Carboniferous limestone in Somerset, Dorset and around Bristol producing hard water.

Moorland reservoirs and river abstraction in the far south west; groundwater and rivers further east.

Triassic sandstone and Mercia Mudstone, with some limestone.

Long-distance transfer from mid-Wales reservoirs via the Elan Valley aqueduct, plus Severn abstraction and Sherwood Sandstone groundwater.

Sherwood Sandstone, Lincolnshire Limestone and Mercia Mudstone.

Derwent valley reservoirs, Trent abstraction and sandstone groundwater.

Lake District volcanics and Pennine gritstone. Little dissolves, so water is soft.

Haweswater and Thirlmere in the Lake District, and Pennine reservoirs, delivered by long gravity aqueducts.

Carboniferous sandstone and gritstone in the Pennines, with Magnesian Limestone along parts of the coast.

Kielder Water — the largest reservoir in the UK by capacity — and the Tyne, Wear and Tees.

Millstone Grit in the Pennines producing soft water, against Chalk on the Yorkshire Wolds and Magnesian Limestone producing hard water.

Pennine reservoirs, Ouse and Derwent abstraction, and chalk and sandstone groundwater, moved around a regional grid built after the 1995 drought.