I purchased 2 for 2 different off grid cabins I have. Just heat up 3 gallons of water, pour heated water in to the canister. Screw on the pump, pump 10 times and viola youve got a hot shower without power. You can even buy pex or plastic tubing and plumb the unit into a proper shower stall and get all the comforts of on grid. This unit is a half gallon more and $37 less than the Zodi off grid shower.