Know the water before you get in
Plain guides to lakes, rivers and the sea, built on the checks swimmers have always made before getting in.
Latest guides
Rivers
Is it safe to swim in UK rivers? Sewage and water quality explained
How river bathing waters are tested and rated, why storm overflows matter after heavy rain, and how to check a UK river before you swim.
5 min read
Lakes
Reservoirs and quarries: why most say no, and the ones that say yes
Why most reservoirs ban swimming, what makes flooded quarries risky, and how managed open water venues in former quarries do things differently.
6 min read
Safety
Lifeguards, flags and designated swim areas
What the RNLI's beach flags mean, why lifeguard hours matter, and how designated swim areas and session times at managed venues change the picture.
5 min read
Rivers
Tidal rivers: can you swim against it?
How the tide pushes up a river and changes its flow, why you shouldn't swim in a tidal river you can't swim against, and how to check the tide.
5 min read
Lakes
Blue-green algae: how to recognise it and when to stay out
What blue-green algae looks like, when blooms happen, the risks to you and your dog, how to check before a swim and who to report it to in the UK.
5 min read
Rivers
Locks, gates and bridges: the man-made river hazards
Why locks, gates and bridges need care, what the Canal & River Trust and Environment Agency say about swimming near them, and why jumping is risky.
5 min read
Lakes
Small, shallow lakes: warmer, and worth checking for algae
Small, shallow lakes warm up faster than big, deep ones. Why that happens, why they're linked to blue-green algae, and how to deal with weed.
5 min read
Sea
Swimming against the tide: can you, and should you?
Could you swim against the tide if you had to? Why even a yes calls for caution, and how to plan a sea swim around the tide.
5 min read
Safety
Who to call if it goes wrong
In the UK, call 999 or 112: the Coastguard at the coast, Fire and Rescue inland. What they'll ask, how to give your location, and what to do with no signal.
4 min read
Rivers
Heavy rain in the last 36 hours? Read this before a river swim
Why heavy rain in the last 36 hours is a reason for caution: faster flow, hidden debris and a higher chance of pollution in UK rivers.
5 min read
You & your kit
The open water kit list, and why you lay it out first
The open water kit list, the four essentials, and the habit that gets you warm faster: laying it out in the order you'll put it back on.
6 min read
Sea
Reading a tide table before you swim
High and low water, springs and neaps, chart datum, and what a tide table can't tell you. How to read one before a sea swim in the UK.
6 min read
Read it here, check it there
Water temperature, tides, rainfall and the official bathing-water rating for 23,000+ spots.