My pet ball python is dehydrated with dry, wrinkly skin! Suggestions please!!?

The vet suggested I bathe him in warm water every night but this has not much efefct. I read somehwere about adding diarolyte to his water/food. Has anyone tried this as I'm a bit dubious? And if so, do you know of any hydration brands that arn't flavoured as I don't think he'll appreciate blackcurrant flavour! Anyone tried their own electrolyte solution or have any other siggestions for rehydrating him? Thanks for reading x