How long does it take to install a 40-gallon hot water heater? The installation of a 40-gallon hot water heater typically takes two to three hours for an experienced professional. Is a 40-gallon ...

This means walk-in tubs require a lot more water to fill. If your water heater has a 40-gallon tank and you have a 50-gallon tub, your hot water might run out before you’re done filling the tub.