The hot water heater is propane gas. All this information is really putting a damper on the summer cabin concept. First, I vacuumed up mouse droppings totally oblivious of hanta virus and now I may just send our place into orbit. The kids are going to wonder why they can't go inside while Mom cleans or messes with the hot water heater. haha I'm only half laughing. Really the information is helpful...just a bit scary. Thanks.