Debate on water quality in rivers, lakes and seas

Water is a devolved policy area, and while comparisons can be made between the different parts of the UK, it is worth noting that these are regulated and governed differently. A brief overview is set out in Table 1:

Table 1 – Environmental regulation of the water sector

England

Wales

Scotland

Northern Ireland

Environment Agency (EA), an executive agency of the Department for Environment, Food and Rural Affairs (Defra)

Natural Resources Wales (NRW), an agency of the Welsh Government

Scottish Environmental Protection Agency (SEPA), an agency of the Scottish Government

N Ireland Environment Agency (NI EA), an agency of the N Ireland Executive

In England, the Environment Agency (EA) is responsible for regulating water quality. This includes monitoring, testing, and maintaining bathing water quality. In Wales, Natural Resources Wales (NRW) has similar responsibilities.

More information about the regulation of the water sector in general (including economic regulation of private water companies in England and Wales) is set out in the Library research briefing Economic regulation of the water industry (August 2024).

Causes of poor water quality

There are several contributing factors to poor water quality. Environmental non-governmental organisation the Rivers Trust assesses that 0% of England’s river stretches are in good overall health.[1]

Agriculture and land management

Agriculture and land management activities can contribute to poor water quality, for example through run-off that picks up fertiliser or livestock pollution. These activities are assessed as contributing to 62% of rivers ranked as having poor water quality in England.[2]

Agriculture is responsible for 50-60% of nitrate, 20-30% of phosphorous and 75% of sediment entering water bodies across England and Wales.[3]

Water company activity – sewage discharges

Water companies contribute to poor water quality in several ways: through discharge of treated or untreated sewage, and through abstraction of groundwater. These activities contribute to 54% of rivers ranked as having poor water quality in England. [4] Sewage discharges have received widespread media attention.

Sewage discharges are the release of raw, untreated sewage into watercourses, such as rivers. These discharges often take place through storm overflow valves, designed to release water from the sewer network when the volume of water is too great for it. Some use of storm overflows is permitted, for example during periods of heavy rainfall, to avoid the sewer network becoming overwhelmed and risking sewage backing up into homes and businesses.

In 2023 there were 464,056 recorded sewage discharges from storm overflows in England, lasting a total of 3.6 million hours. Campaigners argue that many of these discharges are illegal, and a joint investigation from Ofwat and the Environment Agency is ongoing.[5]

For more information on sewage pollution, see the Library research briefing on Sewage discharges (May 2024).

Urbanisation and transport

Urbanisation can contribute to poor water quality through decreasing permeable surfaces and increasing surface water run-off, which in turn picks up more chemicals and transport pollutants than in rural areas. Increasing construction and homebuilding may also increase the volume of pollutants entering urban watercourses. These activities are assessed as contributing to 26% of rivers ranked as having poor water quality in England.[6]

This pack sets out information on water quality statistics, government action, policy and targets, and recent Parliamentary and press material.

[1] The Rivers Trust, State of our Rivers Report 2024, 202, [accessed January 2025]. The Rivers Trust uses data published by the EA under The Water Environment (Water Framework Directive) (England and Wales) Regulations 2017.

[2] The Rivers Trust, State of our Rivers Report 2024, 2024, [accessed January 2025]. The % quoted are all waterbodies with an attribution to these factors (for instance, a river may fail a test of good health for both agricultural and sewage pollution).

[3] Environment Agency, 2021 river basin management plans (PDF), October 2019

[4] The Rivers Trust, State of our Rivers Report 2024, 2024, [accessed January 2025].

[5] Ofwat, Water companies could face legal action after investigation launched into sewage treatment works, 18 November 2021

[6] Ofwat, Water companies could face legal action after investigation launched into sewage treatment works, 18 November 2021