Severn Trent plc is a water company based in Coventry, England. It is traded on the London Stock Exchange and is a constituent of the FTSE 100 Index. Severn Trent, the trading name owned by the company, applies to a group of companies employing more than 15,000 people across the United Kingdom, the United States and mainland Europe, with some involvement in the Middle East. It took its name from the two predecessor River Authorities, which managed the catchment of the Severn and the Trent.

The main companies in the group are Severn Trent Water, Hafren Dyfrdwy and Severn Trent Services. Severn Trent Laboratories was rebranded as part of Severn Trent Services in 2010, to streamline the company and give it a single worldwide image, rather than a series of separate organisations with different identities. As with all water companies in the United Kingdom, Severn Trent is regulated under the Water Industry Act 1991.

The Severn Trent Water Authority was established in 1974. In July 1989, the Severn Trent Water Authority was partially privatised under the Water Act 1989, together with the rest of the water supply and sewage disposal industry in England and Wales, to form Severn Trent Water, with a responsibility to supply fresh water and treat sewage for around 8 million people living in the Midlands of England and also a small area of Wales.

In May 1991, it went on to acquire Biffa, a waste management business. In October 2006, Biffa was demerged from the group Severn Trent and was subsequently listed separately on the London Stock Exchange. In January 2007, the American side of Severn Trent Laboratories was sold to HIG Capital.

In September 2007, the company announced it would be closing its headquarters in Birmingham and relocating to a custom-built office complex in the centre of Coventry in the autumn of 2010.

In 2011 the company acquired East Worcester Water plc, a former statutory water company whose area was surrounded by Severn Trent’s existing water supply area, and the operations were merged.

In June 2016, Severn Trent Water and United Utilities formed Water Plus in preparation for the water market deregulation, to provide retail services for their non-household customers, after being granted approval by the Competition & Markets Authority.

In 2017 Severn Trent plc acquired Dee Valley Water, a water-only company with an area adjoining Severn Trent Water’s own. In 2018 the areas of the two operating companies were adjusted so that Hafren Dyfrdwy (the new name for the Dee Valley company) took on all Severn Trent Water’s water supply and wastewater operations in Wales, and the small area of the former Dee Valley operation within England (an exclave at Chester) became part of Severn Trent Water.