The water heater is the Isotemp Slim 15 and has a reserve of 4 gallons. The water heater is only engine driven. Since there is no shore power on Indecision, the 120 v. power cord has been removed. About 30 minutes of engine time provides about 2-3 warm showers and 45-60 minutes will give 4-6 showers and keep water hot for about 20 hours. I believe this unit is made in Italy. It is nicely made but some of the water connections can be tricky.