Marlow Water Hardness & Quality Report (2026)

South East Water supplies the town of Marlow in Buckinghamshire, providing drinking water to millions across the South East of England. The local supply primarily comes from the Lower Thames Valley groundwater aquifer, utilizing boreholes in the Chilterns area like the Loudwater and Marlow Wells. This is supplemented by river intake from the River Thames at treatment facilities such as the Widmer End or Huntercombe plants. Water undergoes aeration, filtration, chlorination, and fluoridation to meet stringent UK drinking water standards, all overseen by the Drinking Water Inspectorate.

The Thames Valley watershed, including the Chiltern Hills and Berkshire Downs, is geologically defined by the Chalk aquifer. This fractured limestone formation, dating back to the Late Cretaceous era, readily dissolves minerals. As water percolates through these porous rock layers, it picks up significant amounts of calcium and magnesium carbonates, giving the supply its characteristically hard profile. The River Thames itself flows over various Jurassic and Cretaceous strata, including limestones and clays, which contribute a moderately mineralised component to the overall water chemistry.

Homeowners in Marlow will likely notice scale buildup in appliances like kettles, boilers, and showerheads, which can reduce their efficiency and shorten their lifespan. You might find that dishwashers and washing machines require more detergent to achieve the same cleaning power. To combat these effects, regular descaling with vinegar, installing scale filters on taps, or investing in a whole-house water softener are effective strategies. These measures can help extend appliance life, improve soap lathering, and maintain water flow. The water quality consistently meets all Drinking Water Inspectorate standards, with a typical pH range of 7.2–7.6.