Water-quality guide

How to check sea water quality before swimming

A useful water-quality check combines official bathing-water information, recent pollution reports and what you can observe locally.

Quick answerCheck the official bathing-water service for your country, current advice against bathing, recent samples and water-company overflow information where available. “No warning shown” is not proof that the water is clean.

Start with the official bathing-water service

In England, the Environment Agency service provides designated bathing-water classifications and pollution information. Scotland, Wales and Northern Ireland have their own environmental bodies. These records are location-specific and may not cover every beach or entry point.

Check current pollution and overflow information

Water-company event feeds can show reported storm-overflow activity, but coverage, update speed and interpretation vary. Heavy rain can also increase runoff and affect water quality even when a nearby feed shows no active report.

Understand incomplete data

A source may be delayed, unavailable or outside the area Seyva can match. When Seyva says a check is incomplete or unavailable, treat that as missing information—not as a clean result. Always open the named official provider where uncertainty matters.

Use your senses, but do not rely on them

Visible sewage debris, discoloured water, unusual odour, dead wildlife or warning signs are reasons not to enter. Clear-looking water can still contain contamination, so appearance alone cannot confirm quality.

  • Check official advice as close as possible to the session.
  • Consider recent rainfall and local runoff.
  • Look for beach notices and temporary warnings.
  • Avoid entering when the data is missing and local risk is unclear.
  • Seek medical advice if you become unwell after contact with polluted water.
Written and reviewed by Ollie BartlettFounder of Seyva and a sea swimmer and paddleboarder based near Worthing. Reviewed 14 September 2026. Seyva is a planning aid, not professional safety advice.