A storage tank heater will be the best alternative to the quick filling of the water bath with the hot water. A tankless water heater can provide a continuous supply of hot water. While a smaller water heater can still work, you may not be able to fill the tub completely, or you may have to come up with other ways to heat water for a bath.
The question of whether an instantaneous water heater can fill a bath is certainly one of the most popular questions we get (daily!) regarding water heating. If you are looking for a way to heat water quickly and efficiently for your bath, you might be wondering if an electrical instantaneous heater can do the job. A heater with low capacity can't fill a bathtub.
Bathing needs lots of hot water. Small heaters can't provide enough water. Bigger heaters are better for baths.
Upgrade might be necessary for more water. I installed a 95 gallon bathtub as well as a very large shower with 4x shower heads and we installed a Rheem 60 Gallon hybrid heat pump water heater and it is amazing! The water heater has both electric coil heaters like a traditional water heater, but also has the high efficiency heat pump. Will a tankless water heater fill a tub? Because tankless water heaters can continuously produce hot water, they can supply enough hot water to fill a bathtub.
Finding the best water heater tub solution is crucial for homeowners seeking rapid, efficient, and consistent hot water for large or specialty bathtubs. A relaxing soak can quickly turn frustrating if your hot water runs out halfway through filling the tub. Unlike whole-home water heating systems, a heater dedicated to a bathtub must meet higher volume and reliability standards.
The right. As a construction industry rule of thumb, the water mixture for a comfortable bath is roughly two-thirds (2/3) hot water to one-third (1/3) cold water. Since the typical water requirement to fill a regular size walk-in tub is 40-50 gallons depending on the user's size, roughly 30-35 gallons of hot water will be needed for the fully filled occupied tub.
As a point of reference, Some. A 24 kW electric tankless water heater can fill a standard 40 gallons bathtub in about 7 to 15 minutes time depending on the cold water temperature. It is unlikely that you can use an electric tankless water heater to fill a large bathtub within an acceptable duration.
Using an electric tankless water heater to fill a standard bathtub is fine. 10 best bathtub water heater reviewed and rated for 2026. Find the best bathtub water heater for your home available on Amazon.