What Is Occupied vs Unoccupied Water Capacity on a Walk-In Tub?

Water capacity on a walk-in tub is stated as two numbers. Unoccupied capacity is how many gallons the tub holds with nobody in it. Occupied capacity, sometimes written as the occupied range, is the amount of water you actually use once a bather is seated and displacing water. Ella spec sheets print both, and the occupied figure is the one to use when sizing your water heater.

How It Works

Your body takes up space in the tub, so the water level rises around you and less water is needed to reach the same depth. That is why occupied capacity is given as a range: the actual volume varies with bather size, so a smaller bather typically uses the upper end and a larger bather the lower end. A few examples from the current spec sheets: the Standard holds 65 gallons unoccupied and 30 to 50 gallons occupied, the Elite 75 and 35 to 55, the Big4One 127 and 75 to 100, and the ShaK 145 and 80 to 120. Fill time is capacity divided by the real-world flow at your faucet, which is why the occupied figure is the better guide to a fill. The full table is in water capacity by model.

Which Ella Models Have It

Every Ella walk-in tub has an unoccupied and an occupied capacity, and the current spec sheets print both for nearly every model. Three exceptions: the Monaco, Mobile and LayDown60 capacities are not printed on the current spec sheets, so please check the live product page or ask the team rather than rely on older figures. Use gallons only; the litre figures printed on the Big4One sheet are misprints. Reading the rest of the sheet is covered in how to read an Ella spec sheet.

What to Know as an Owner

Use the occupied range to size your hot water. A 75 gallon or larger house water heater is recommended for the average walk-in tub, and the largest models such as the ShaK and the Big4Two may need a dedicated additional heater. Remember that the in-line heater on hydro massage tubs maintains bath temperature while the pump runs; it does not heat cold water, so your house water heater does all the work of filling the tub hot. Pressure, pipe size, distance from heater to tub and other fixtures running at the same time all matter, so have your contractor assess them with hot water heater requirements in hand.

If the tub fills slower than you expected, compare the occupied figure with your faucet's real flow before assuming a fault; fast-fill faucet expectations explains what changes it. When you open a ticket at ellasbubbles.com/support or call (800) 480-6850 about fill time or hot water, have your model name, your water heater size and type, your supply line size, and a timed fill ready.

Related Guides

• Using an Ella Walk-In Tub With Well Water and a Septic System
• What Is the Total Weight Capacity of a Walk-In Tub?
• How Does a Walk-In Tub Compare to a Hot Tub?
• What is the Ella Big4One walk-in tub and what do owners say?
• How much water does a walk-in tub actually use per bath?
• How Many Gallons Does the LayDown 30x60 Hold When Occupied?

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