Thames at Windsor and Eton is a lovely place to swim. Have no issues. Have previously swum with the kids further upstream when we lived in Oxon. Biggest issue is boats. Will be using a Swimsafe buoy from now on.

Personally, I love sea swimming. Rivers are just too flat. And not enough salt for my buoyency.

Further to the comments in made about Hayling earlier in the thread, we have a FB Group that issues out conditions and other water related comments around Chi Harbour and Langston… also includes North Solent beaches (Meon Shore etc.)

Called; Hayling Sewage Watch

Alos issued “Brown Alerts” these are our interpretation of Southern Waters Press Release notifications about Sewage Outfalls etc. (there is one out now since all the rainfall so we have a Brown Alert in place)

The North Tyne is a stones throw away..lots of the local yoof swim in it ..as I did as a kid.
One of the cleanest rivers in this part of the world is the Coquet ..in Upper Coquetdale, Northumberland..(Cheviots).
I often see folk swimming in it as I’m heading up towards the Border Ridge from Alwinton ..