SES Water Tap Water Quality

SES Water supplies Surrey & Sussex with drinking water drawn from chalk aquifers of the North Downs and greensand layers across Surrey, with some Reigate and Redhill boreholes.

SES Water (formerly Sutton and East Surrey Water) is one of the smaller independent water companies, serving the suburban Surrey and Sussex areas south of London. The supply draws primarily from the North Downs chalk, producing moderately hard to hard water at 180–240 mg/L CaCO₃. The company has a notably clean compliance record — SES Water has received no active DWI enforcement notices in recent years, which distinguishes it from most other UK water companies. Nitrate levels are generally low to moderate. Lead compliance in older areas is actively managed through corrosion inhibitor dosing.

Typical water profile

With typical hardness of approximately 200 mg/L CaCO₃, water in the SES Water supply area is classified as hard. Some limescale buildup is normal — regular descaling of kettles and coffee machines is recommended.

Notable: Hard water from North Downs chalk (180–240 mg/L). Clean compliance record — no active DWI enforcement notices. Good overall water quality for the region.

Is SES Water water safe to drink?

Yes. All treated water supplied by SES Water meets the UK Drinking Water Regulations. The Drinking Water Inspectorate (DWI) audits every water company annually — SES Water serves 0.7 million customers across 21 supply zones. Each zone is tested thousands of times per year and results are published in the annual compliance report.

However, water quality varies significantly between zones within the SES Water supply area. Your specific zone may have different hardness, nitrate, or THM levels from your neighbour in a different zone. That's why it's worth checking your exact postcode above.

How to check your SES Water zone

Enter your postcode in the box above to see zone-specific data for your address — including hardness, nitrates, lead, chlorine, fluoride, and THMs — drawn directly from SES Water's most recent annual compliance report.