What should I check after heavy rain before sea swimming?

Why rainfall matters

Rain can wash material from roads, land and drainage systems towards the coast. The effect varies with the amount and timing of rain, local drainage, rivers and the exact beach. A town-level weather forecast cannot tell you the water quality at every entry point.

Use the named official source

Open the relevant bathing-water service or environmental agency information close to the planned session. Look for current advice against bathing, recent sample information and any local notice. Check what area and date the information actually covers.

Understand the limits of the data

An overflow or pollution feed may be delayed, incomplete or unavailable for the place you have chosen. No warning shown does not prove that the water is free from contamination. Visible debris, unusual odour, discoloured water or a local sign are reasons to change the plan.

Before you go

• Check official bathing-water information as close as possible to the session.
• Consider recent rainfall and the nearest river, stream, outfall or urban drainage route.
• Look for temporary signs and local notices when you arrive.
• Do not use clear-looking water as the only quality check.
• Use Seyva’s water-quality status as one input and open the provider when the result is uncertain.