While standard bathtubs have a capacity of 24 gallons, most people do not fill the tub to capacity when taking a bath. When you sit or recline in the tub, your body takes up some of the volume of the tub, limiting the tub’s capacity to hold water. Your body may take up the volume of space in the tub such that you only need 10 to 15 gallons of water to reach the tub’s capacity when you are in it.
Custom bathtubs offer a greater water capacity and more options for sitting and reclining. These tubs are meant for luxury and relaxation and often have special features such as sloping backs and built in armrests, which also take up some of the basin’s capacity. With water capacities of 45 to 80 gallons from many manufacturers, a custom bathtub can hold two to three times as much water as a standard one.
If you are concerned about the amount of water used in your home, there are several things you can do while still enjoying a soak in the tub. First, use a tub plug that does not leak. When bathing babies and young children, only put an inch or two of water into the tub for safety.