When I go with my 3 year old son to the swimming pool, I want him to take a shower after swimming, since it is not healthy to leave pool water on your skin. But before we get home, he usually falls asleep, so I want to wash him at the pool. Problem is, the showers there do not have hot water. I can wash myself with cold water, but my child naturally hates it.
Is there a way I can somehow heat the water, so that my son will have a more pleasant shower?
Consider to pick up a "bag shower," often used in camping environments. If you have a tall vehicle, you can hang it usefully high, letting it warm in the sun, to reach the desired temperature. Using "camp bag shower" on Amazon results in far to many to direct to a single link, plus some are not hanging type and have a foot pump to dispense the water via shower wand, a nice feature. Prices range from just over ten bucks to many multiples of that, depending on size and quantity of the purchase.
You would place the selected item in the sun and if it gets too hot, make the spray travel a longer distance to the youngster, cooling slightly from evaporation during the transit.