What are the health risks in seawater?
Most water-borne diseases are linked to the presence of human or animal faeces (faecal contamination).
The main ailments caused by bathing in contaminated waters are:
- gastrointestinal (digestive tract) - such as dysentery
- respiratory infections
- ear, nose and throat complaints
Why are coastal waters affected by faecal contamination?
Direct sewage discharge, sewage from stormwater overflows and water running off from streets and farmland (often through streams and rivers) can all affect the quality of coastal water.
The degree of pollution from these sources varies from beach to beach, depending on the proximity of any sewage discharge and the type of sewage treatment used locally.
Weather can also affect pollution.
The quality of bathing water drops 24 to 48 hours after heavy rainfall. This is because combined sewage overflows (CSOs), which divert excess sewage from treatment plants into rivers and the sea to prevent flooding, are operated more frequently during storms.
There is also a greater risk of the sea being affected by polluted water draining from farmland after heavy rain.
Who monitors the quality of bathing water?
The UK, in line with other European Union members, is required to identify popular bathing beaches and test the water for faecal contamination during the summer season.
Each bathing beach is given one of the following annual classifications:
- Excellent - the highest, cleanest class
- Good - generally good water quality
- Sufficient - the water meets minimum standards
- Poor - the water has not met the new minimum standards. Work is planned to improve bathing waters not yet reaching Sufficient.
If water is classified as "poor" one year, you are advised not to swim - there'll be an "advice against bathing" symbol on signs at the beach and online.
To view a list of the beaches that were tested and the results of those tests, see:
The results of the previous summer's environment agency tests (see above) are also used by the Blue Flag and Marine Conservation Society award schemes to recommend beaches.
How to avoid polluted water
To minimise the risks of swimming in polluted water, pick a Blue Flag beach or an MCS-recommended beach.
If it's been raining heavily, stay out of the water for at least 24 hours.
Both the Blue Flag and the MCS award schemes (more details below) only include beaches that have met the higher EU standards (or in the case of the MCS recommendations, stricter criteria).
Beaches recommended by the Marine Conservation Society
The Good Beach Guide is published by the Marine Conservation Society (MCS) and indicates which UK beaches have excellent water quality.
By clicking on the guide's interactive map, you can find out about more than 1,000 beaches in the UK and Ireland. You can find out about the quality of bathing water, if the beach has lifeguards and if there are facilities such as toilets and parking available.
The MCS recommendation for bathing quality is the highest standard of any UK award for bathing water quality. It uses the government agencies' data but applies stricter criteria than those of the EU's higher guideline standards.
The Blue Flag Scheme for beaches
The Blue Flag Scheme is awarded annually to beaches that meet high standards of management, promote environmental care, and have attained high standards for water quality in the previous summer season.
All beaches awarded the Blue Flag must meet the higher EU bathing water standards. The Blue Flag is therefore another useful indicator of good quality bathing water. You can check which beaches have been awarded the Blue Flag.
How can I check the current status of bathing waters?
During the summer months, the Environment Agency posts the results of its weekly tests of bathing water quality in England and Wales on its website.
In Scotland during the summer, SEPA provides daily information on the predicted water quality at 11 of its beaches. These forecasts are available on its website and from a telephone helpline: 0845 230 3098.
Article provided by NHS Choices