Church Street Water Hardness & Quality Report (2026)

Residents in the central west London Westminster–Marylebone distribution zone receive their water from Thames Water. The supply originates from the River Lee, specifically a chalk-tributary source. This water is then treated at the Lee Valley Water Treatment Works before being distributed to homes and businesses. The utility aims to provide a reliable water supply, though specific details on the exact sources and treatment processes require further official data.

The water's hardness is a direct result of its geological origins. The supply is drawn from chalk aquifers, which are formed from porous chalk bedrock. As water flows through this chalk, it dissolves minerals, primarily calcium and magnesium, leading to significantly high hardness levels. This chalk geology is characteristic of many water sources in the region, contributing to the naturally very hard water found in this part of London.

With water hardness reported at 19.2°Clark, you'll likely notice its effects on your appliances and plumbing. Scale buildup can become a problem in kettles, coffee makers, and especially water heaters, potentially reducing their efficiency and lifespan. Soap and detergent may not lather as readily, requiring you to use more product. If you're experiencing issues with scale or want to improve soap performance, a water softener is often recommended for homes in this area. Regular descaling of appliances can also help mitigate some of these effects.