When I put the 6 gallon water heater in our
Trillium I did lots of searching the www and found, somewhere, a 4 gallon water heater. As I recall it was not much smaller than the six gallon and about the same $ so I went for the 6 gal unit. We have depleted the six gallon tank doing dishes and outside showers/hair washing so I can't imagine having much less hot water than the 6 gallon tank provides.YMMV