Water privatisation was undertaken in 1989 by the government of Margaret Thatcher which partly privatised the ten previously public regional water authorities (RWAs) in England and Wales through the sale of assets. The regulatory arm of the RWAs, including pollution control and water resource management, was hived off to the newly created National Rivers Authority.
At the same time the economic regulatory agency Ofwat was created, following the model of infrastructure regulatory agencies set up in other sectors such as telecommunications and energy. The Drinking Water Inspectorate (DWI) was set up in 1990 to monitor water safety and quality.
There are sixteen mostly smaller water only companies in England and Wales that have been privately owned since the 19th century. In Scotland and Northern Ireland water and sewerage services have remained in public ownership.
Water privatisation in England and Wales remains controversial. A 2001 study by the Public Services International Research Unit stated that
At privatisation the industry's £4.95 billion debt was written off. Privatisation critics argued in 1997 that infrastructure—particularly sewers—was not adequately maintained and that Ofwat implicitly "gave (its) approval to running down the underground network". Furthermore, Ofwat was accused of not comparing company performance with targets, not relating performance standards with past or projected levels of investment, failing to "publish information in a consistent form" and not requesting that levels of service indicators become mandatory. Instead company licenses were renegotiated to address performance issues. The critics concluded that in the "conflict between making profits and providing a certain level of services" the legislation "resolves it in favor of profit".
It was alleged that the consequences of the 1988 Camelford water pollution incident were covered up partly because prosecution would "render the whole of the water industry unattractive to the City".