Water and health

Clean water is vital for our health and wellbeing.

In Wales, water companies supply drinking water that is wholesome and safe, in accordance with relevant water quality standards. Water not supplied by water companies – a ‘private’ supply – is also monitored and assessed against drinking water standards to ensure its quality. About 80,000 people in Wales have a private water supply.

The Drinking Water Inspectorate provides independent reassurance that water supplies in England and Wales are safe.  This includes checking that water companies supply water that is acceptable to the public.

Health risks

The greatest risk comes from microbial contamination.  The main source of microbes such as bacteria and viruses is from the drinking water contaminated with faeces from humans or animals (including birds).  Other microbial hazards include Legionella, a bacteria that can grow in water systems, and toxic blue-green algae (more correctly called cyanobacteria) that can grow in lakes and reservoirs. 

Chemicals can also affect water quality.  Sources of chemicals in water include:

• chemicals from industrial or agricultural activities such as pesticides and heating oil
• naturally occurring chemicals such as rocks rich in metals such as arsenic and iron
• chemicals from the water treatment process
• from materials that come into contact with water such as pipes made from lead

The main radiological hazard is radon, a naturally occurring radioactive gas, that can sometimes be found in drinking water.

Water companies have water safety plans to manage the risks from microbes, chemicals and radiological hazards in drinking water and to ensure that they meet health-based standards.  These plans include drinking water treatment processes including disinfection and filters to remove contaminants and quality control such as monitoring water quality at source and at the consumers tap.

Our role

Public Health Wales works with water companies, local authorities and others to ensure water is of the highest quality.  One way we do this is through the Water Health Partnership for Wales which brings together a range of professionals to work on issues related to water and health.  Current work includes managing risks from lead in drinking water, private water supplies, bathing waters and drought.

Occasionally water contamination events occur and when this happens we work with others to assess the potential impact on health and ensure appropriate measures are quickly put in place to safeguard the public.

If you are concerned about the quality of your drinking water, we recommend you contact your water company in the first instance or your local authority if you are on a private water supply. If you have public health enquiries, please contact Public Health Wales.