Caterham Water Hardness & Quality Report (2026)

Residents of Caterham, Surrey, rely on South East Water for their daily supply, a utility that covers a vast area of East Surrey, West Kent, and Sussex. The water originates almost entirely from groundwater, with numerous boreholes drawing from the Chalk aquifer. Important abstraction points include the Netley and Burstow boreholes, which feed treatment facilities like the Caterham and Kenley plants. This extensive network serves more than 2 million customers across 3,700 square kilometers, with water naturally filtered as it percolates through the North Downs and the Upper Chalk aquifer within the Anglo-Paris Basin syncline.

The underlying geology is dominated by Cretaceous Chalk, a type of karstic limestone formed from ancient marine microfossils. This porous rock, often containing flint nodules, allows rainwater to seep through over long periods. As the water percolates, it dissolves calcium and magnesium bicarbonates from the limestone bedrock. This natural process, characteristic of regions like SE England and its Wealden anticline structures, results in a significantly hard water supply, as there is little dilution from surface water sources.

This very hard water can lead to noticeable limescale buildup in household appliances and plumbing. You'll likely see it on kettles, showerheads, and inside water heaters, reducing their efficiency and lifespan. Dishwashers and washing machines may also experience issues with clogged heating elements. To manage this, regularly descaling with vinegar, installing limescale filters, or lowering your water heater's temperature to below 60°C can help. For the most effective protection against damage and to improve how soap lathers, installing a whole-house water softener is highly recommended in this area. South East Water monitors its supply closely, reporting a typical pH between 7.2 and 7.6, and ensures compliance with UK drinking water standards, with no specific concerns regarding PFAS or other contaminants identified in routine testing.