In England and Wales the main responsibility for ensuring our drinking water is clean and “wholesome” lies with the water companies which supply it. The standards they must meet are set out in the Water Supply (Water Quality) Regulations 2016.
Part III of the Regulations prescribes standards of wholesomeness in respect of water that is supplied for cooking, drinking, food preparation, washing and other domestic purposes, and for commercial food production purposes. Permitted levels are set within the Regulations for chemicals such as lead, mercury and fluorine, as well as for microbiological contaminants such as E.coli and other coliform bacteria.
At a national level, the Environment Agency is the government body responsible for making sure that the quality of water resources does not deteriorate and that it is improved when necessary. The Drinking Water Inspectorate, part of the Department for Environment, Food and Rural Affairs, oversees the quality of public drinking water supplies.
At a local level, local authorities are responsible under the Water Industry Act 1991 for keeping themselves informed about the wholesomeness and sufficiency of water supplies in their area. Where a local authority considers that the public water supply may become unwholesome or insufficient, it must inform the water supplier, which must then take appropriate action.
Environmental health professionals play a key role in protecting local water quality. As well as sampling the public water supply from time to time, they are responsible for identifying and checking thousands of private water supplies, big and small, under The Private Water Supplies (England) Regulations 2016 in England and their equivalents in the other parts of the UK. Where problems with such supplies are discovered, EHPs work with those who provide them to ensure that the water is improved. If necessary, they can take legal action to achieve this.
Local authorities are responsible for providing information on the quality of over 400 mainly coastal ‘designated bathing waters’ during the annual bathing season (15 May - 30 September). Based on the results of laboratory tests carried out by the Environment Agency, signs maintained by councils must provide a summary of the quality of the bathing waters, including factors that can affect the water like nearby sewage overflows or rivers, together with additional information about any 'abnormal situations' that affect bathing waters, for example a breakdown at a sewage pumping station or a slurry spill and, if the pollution could affect people swimming or paddling, how long it’s expected to persist.
Based on sampling data taken over 4 years bathing waters are classified as either excellent, good, sufficient or poor. If a bathing water is classified as ‘poor’, a council has to display an 'advice against bathing' symbol. Councils must also display information on the causes of pollution and measures to clean it up.
The quality of water in swimming pools is regulated under the Health & Safety at Work etc Act 1974.