Is it safe to drink tap water?

02/12/2019 Océane Bidault

The UK has rigorous national standards that govern the quality of drinking water. According to tests by the Drinking Water Inspectorate (DWI), 99.95% of public water supplies complied with the national standards, meaning only a tiny proportion of tap water in the UK could be deemed as ‘unsafe to drink.’ Water suppliers take on the responsibility to manage the quality of the water they provide, while the Drinking Water Inspectorate monitors public water systems to ensure your tap water meets the enforceable standards.

While your tap water may not be entirely contaminant-free, it should not contain a level of contamination that could pose a threat to human health. Further, if a water company becomes aware of potential contamination, or a violation of the national water standards, the water supplier has to issue advice regarding the risk to customers, as a precaution.

What defines safe drinking water?

According to the DWI, safe drinking water is a supply that does not exceed pre-defined levels of specific pollutants such as lead, nitrates, or common pathogens — thus, making it safe for human consumption.

In the UK, drinking water must be ‘wholesome’ and of an acceptable quality to consumers, as articulated in the Drinking Water Directive 1998. The directive establishes a health-based standard for the quality of public drinking water and is based on evidence from the World Health Organisation’s ‘Guidelines for Drinking Water Quality.’ This ensures water suppliers test their water on a regular basis and enforce strict controls over a range of factors including micro-organisms, chemicals like nitrates and pesticides, heavy metals such as lead and copper, as well as how to water looks and tastes.

If you are concerned about the quality of your local tap water, you have the right to contact your water company and request they respond to your concerns. If they fail to respond, contact the DWI.

Where in the UK is tap water unsafe to drink?

1. Lancashire

In 2015, animal waste seeped into the underground storage tank of water firm United Utilities. The waste contaminated the local drinking water supply with a parasite known as cryptosporidium, which can cause fever, vomiting and diarrhoea if consumed by humans. The contamination affected up to 700,000 consumers in the local area as the utility company issued a boil water alert. In Preston, consumers couldn’t drink their tap water for one month. United Utilities had to pay a fine for providing water that was unfit for human consumption and has since introduced new measures.

2. Bristol

In 2018, schools around Bristol were closed as a spate of diarrhoea and vomiting struck the city following the discovery of a parasite in the local water supply. Residents were told to avoid drinking from their taps or preparing food with tap water as Bristol Water issued a 48-hour boil water notice to residents in the Clevedon area. The advice was due to the same cryptosporidium parasite discovered in Lancashire.

3. Worcester

On 1^st March 2019, Pure Water Environmental Services Limited pleaded guilty of supplying contaminated water to 83 residential apartments in Worcester. An investigation followed customer complaints of a chemical taste and odour in the building’s water supply. Following analysis, authorities found a water tank on the private water supply system for the development was contaminated with solvents used during a refitting exercise.

One in two people in the UK are concerned about the quality of their tap water

Consumers are concerned that their public supply contains lead, bacteria, carcinogens and micro-plastics. Although it is very rare to see cases of waterborne disease resulting from inadequate treatment in the United Kingdom, localised contamination is an ever-present risk. By staying aware of regional water alerts, you’ll be first to know should your local tap water supply become unsafe.