Do walk-in tubs use more water than a standard bathtub?

Not necessarily, and often less than the spec sheet suggests. The water an Ella walk-in tub actually uses is its occupied figure, 30 to 75 gallons per bath for most standard-size models, because the tub fills only after you are seated and your body displaces part of the water. The larger unoccupied figure printed on the sheet, 65 to 107 gallons for those same models, describes a tub with nobody in it. The right comparison is the occupied figure for the model you are considering against how full you run your current bathtub, and every model's pair of figures is in How much water does a walk-in tub actually use per bath?.

Why the Spec Sheet Number Overstates What You Use

Ella spec sheets print water capacity as two numbers. Unoccupied capacity is how many gallons the tub holds with nobody in it. Occupied capacity, written as a range, is the amount of water you use once a bather is seated and displacing water. Your body takes up space, so the water level rises around you and fewer gallons are needed to reach the same depth. The occupied figure is a range rather than a single number because the actual volume varies with bather size: a smaller bather typically uses the upper end of the range and a larger bather the lower end.

Three cautions when you read a sheet:

• Use gallons only. The litre conversions printed on some sheets, including the Big4One sheet, are misprints.
• The Monaco, Mobile and LayDown60 capacities are not printed on the current spec sheets, so check the live product page or ask the team rather than relying on older figures.
• When you estimate a fill, use the occupied figure, since fill time is capacity divided by the real-world flow at your faucet.

Water Used per Bath, Model by Model

The spread in this table is the real answer to the question. Whether a walk-in tub uses more water than the bathtub you have now depends far more on which model you choose than on the fact that it has a door. The Petite, Standard, Zen and Flow all hold 65 gallons unoccupied and use 30 to 50 gallons per bath, the lowest figures in the line, while the two-seat Escape and the long-seat ShaK sit at the top. There is no single gallon figure for a conventional bathtub to set against these, so measure your own habit honestly: a bather who fills a standard tub to the overflow every night is comparing against a very different number than one who runs a few inches of water.

Why the Bathing Sequence Changes the Comparison

A regular bathtub is an open basin you climb into over a high wall after it has filled. A walk-in tub's door is part of the tub wall, so it has to stay closed while there is water inside. You get in first, close the door, then fill; after the bath you open the drain, wait, then open the door. That sequence is the reason the occupied figure is the one that counts, and it is also why Ella pairs its seated tubs with a fast-fill faucet, 16 GPM on the 2-piece set and 18 GPM on the 5-piece set at ideal home plumbing, and with gravity-driven dual 2 inch drains that typically empty the tub in two minutes or less once connected to a proper 2 inch drain line. The glossy acrylic shell acts like an insulator while the water is around you, and heated seats are an option for extra comfort during the fill. The full set of practical differences, including entry, seating and cleaning, is in Walk-In Tub Versus a Regular Bathtub: Seven Practical Differences in Entry, Seating, Fill and Drain, Water Use, Electrical, Installation and Cleaning.

Hot Water Is the Constraint That Actually Bites

For most homes the question behind the question is not the water bill but whether the water heater can deliver the whole fill warm. A fast faucet only helps if the water stays hot for the entire fill, and the general guidance from the team is that the average walk-in tub usually calls for a 75 gallon or larger water heater, with the recommendation being the maximum capacity heater available for your house. The largest tubs, such as the ShaK and Big4Two, may require a dedicated additional heater. If you have a tankless heater, it should be rated at 11 GPM or more. The Transfer60 line in the table above, 55 to 75 gallons occupied, is the range staff cite when a small tank runs out halfway through a fill.

What to have your contractor check before installation day:

1. Water heater capacity against the occupied figure for your model, with the ShaK and Big4Two flagged for a possible second heater.
2. House water pressure, pipe size and the distance from the heater to the tub, since all of these change the real-world fill rate.
3. Three quarter inch supply lines with accessible shut-off valves, which Ella recommends; both fast-fill faucet sets include two 5 foot braided supply lines.
4. A 2 inch drain line, so the two 2-inch gravity drains can empty the tub as designed. Drainage and Fill Time explains why no pump is involved.

Models That Fill Differently

Two exceptions are worth knowing. The HomeCare Transfer Bathtub has an 80 gallon internal tank that pre-heats water while the bather is being prepared, so the tub fills in about 90 seconds after the bather is seated, drains in about 150 seconds, and the tank refills in about 11 minutes for the next bath; it is built for caregiver-supervised bathing only. The LayDown60 is never sold with a factory faucet, so its fill rate depends on the customer-supplied faucet your plumber installs. For everything that decides the wait between sitting down and starting your bath, see How long does it take to fill a walk-in tub?.

If you are deciding between two models on water use, ask your Ella dealer or the team at (800) 480-6850 for the current spec sheet of each and compare the occupied ranges side by side.

Related Guides

• What Size Water Heater Do I Need for My Walk-in Tub?
• How fast will my walk-in tub fill? Fast-fill faucet expectations and operation

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