Wessex Water Services Limited, known as Wessex Water, is a water supply and sewerage utility company serving an area of South West England, covering 10,000 square kilometres including Bristol, most of Dorset, Somerset and Wiltshire and parts of Gloucestershire and Hampshire. Wessex Water supplies 1.3 million people with around 285 million litres of water a day.

It is regulated under the Water Industry Act 1991. In 2016, the company had about 2,100 employees.

Wessex Water is owned by the Malaysian power company YTL Corporation. Its headquarters are on the outskirts of Bath in Claverton Down.