Until which age would you let your children pee in a puplic pool?

Depends on his mental state. If he was 33 and retarded, i would still let him do it.

Obviously until they are fully toilet trained, so depends but 3 or 4-years-old at the latest. Until they are full toilet trained, they are going to pee in the pool regardless of whether you want them to or not.

Yes, there are swim diapers but those don't function like normal diapers because they are designed to only contain poo, not pee. If they functioned like normal diapers, they would just absorb the pool water.