Rotherhithe Water Hardness & Quality Report (2026)

Thames Water Utilities Limited provides Rotherhithe's water supply, drawing from a mixed network. This includes groundwater from the London Basin chalk aquifers and surface water from the River Thames and its reservoirs like Queen Mother Reservoir and Wraysbury Reservoir. Key treatment facilities, including Coppermills Water Treatment Works and Hampton Water Treatment Works, meticulously process this raw water. The treatment involves coagulation, filtration, chlorination, and fluoridation before the water is distributed across South East England to millions of customers.

The underlying geology is dominated by the Cretaceous Chalk aquifer, a white limestone formed during the Late Cretaceous period. This porous, karstic formation, part of the London Basin, allows groundwater to dissolve significant amounts of calcium and magnesium as it percolates through the rock. Surface water sources also interact with calcareous sediments, contributing to the water's mineral profile. These geological factors naturally result in a hard water supply due to the abundance of dissolved bicarbonates from limestone dissolution over vast geological timescales.

This very hard water can lead to noticeable limescale buildup in appliances like kettles, boilers, and showerheads, potentially reducing their efficiency and lifespan. You might observe white deposits and clogged pipes, contributing to higher energy usage. Homeowners can manage this by regularly descaling with vinegar, installing scale filters on taps, or lowering boiler temperatures. For significant protection against appliance damage and to improve soap's lathering ability, a whole-house water softener is strongly recommended. The water's pH typically ranges from 7.5 to 8.0, and Thames Water confirms compliance with UK drinking water standards.