Our health inspector allows us to fill an Igloo cooler with hot water and place it above a basin or bus tub for catching the drain water and use it for handwashing at festivals. You have to buy a different spigot that stays open instead of the pushbutton one that comes on the Igloo, but they're easy to find and install. We use a propane demand hot water heater for hot water for our sink at outdoor events. Works great.