Tap Water Quality in Plymouth

Tap water in Plymouth is provided by South West Water, which serves South West England. The water in this area is classified as soft, with a typical hardness of around 50 mg/L CaCO₃. This means minimal limescale buildup — your appliances are unlikely to suffer from calcium deposits.

UK tap water is among the safest in the world, with over 99.9% of tests passing legal standards each year. However, hardness levels, trace contaminants, and the presence of disinfection byproducts like trihalomethanes (THMs) vary significantly by zone — even within the same city. That's why it's worth checking your specific postcode.

How hard is Plymouth water?

Plymouth's water hardness of approximately 50 mg/L CaCO₃ places it in the soft category. Soft water in Plymouth is a result of upland reservoir sources rather than chalk or limestone.

For context, hardness below 60 mg/L is considered very soft, 60–120 is soft, 120–180 is slightly hard, 180–250 is moderately hard, 250–310 is hard, and above 310 mg/L is very hard. The UK average is around 150–200 mg/L.

Should I filter my water in Plymouth?

UK tap water is safe to drink straight from the tap without filtration. With soft water like Plymouth's, filtration is less of a necessity for limescale — but a good quality filter jug can still improve taste by reducing chlorine and trace compounds. Reverse osmosis systems remove the widest range of contaminants including nitrates, THMs, and any trace PFAS compounds.