SES Water is the UK water supply company to its designated area of east Surrey, West Sussex, west Kent and south London serving in excess of 282,000 homes and businesses and a population of approximately 675,000 people.

An area of 322 square miles (830 km2), extending from Morden and South Croydon in the north to Gatwick Airport in the south, and from Cobham and Dorking in the west to Edenbridge and Bough Beech in the east forms the company’s supply area.

East Surrey Water and Sutton District Water merged in 1996 to become Sutton and East Surrey Water plc. It had its head office in Redhill and moved into a new building on London Road on 2000. It is responsible for water supply to an area of 322 square miles (835 km2), providing this service to a population of 655,000 and to some 17,000 businesses, including Gatwick Airport. It produces around 35 million imperial gallons (160 Ml) of treated water per day, which is delivered through 2,100 miles (3,400 km) of water mains. In order to achieve this, it maintains 31 operation service reservoirs and water towers, 23 pumping stations, eight treatment works, and has one surface reservoir, at Bough Beech, near Edenbridge, Kent. The treatment works are at Cheam, Elmer (near Leatherhead), Cliftons Lane in Reigate, Woodmansterne, Kenley, Godstone, Westwood (Clacket Lane, Tatsfield parish) and Bough Beech. In October 2021 consumers supplied by the Westwood treatment works (properties in and around Oxted) were warned to boil all drinking water because of contamination by E.coli.

Sutton and East Surrey Water are undertaking a series of major improvements, to ensure that all properties can be supplied with water from more than one works. This is being achieved in three stages, corresponding to the Asset Management Plan (AMP) funding periods for UK water companies. Under AMP5, which covers 2010 to 2015, the capacity of Bough Beech works was increased from 45 Mld (megalitres per day) to 55 Mld, and two new trunk mains were installed. This increased the proportion of the area of supply connected to two works from 11 per cent to 36 per cent. This will be further increased to 56 per cent under AMP6, covering 2015 to 2020, by increasing the capacity of Woodmansterne works from 35 Mld to 50 Mld, upgrading the Woodmansterne pumping station, and installing another four trunk mains. During AMP7, covering 2020 to 2025, they hope to have all customers supplied by more than one works, by a further upgrade to Bough Beech works, increasing its capacity from 55 Mld to 70 Mld, and installing the final two trunk mains.

Sutton and East Surrey Water plc was rebranded to SES Water plc in February 2017 and is now trading as SES Water.