Chlorine-free swimming pools

[AngelDog]

I have a child who reacts to chlorine but he needs to learn to swim. Does anyone know of any chlorine-free swimming pools which could be accessed within half a day's travel of Berkshire, Reading? I can get to London pretty easily, and anywhere on the train line to the south west of England, or to Oxford.

I've almost taught him to swim on family holidays on the continent in outdoor swimming lakes, but I'd like to be able to do some more back here.

Thanks a lot.