What water pressure does a walk-in tub need to fill quickly?

Ella fast-fill faucets are rated at 60 PSI: the 2-piece set is designed for 16 gallons per minute and the 5-piece set for 18 gallons per minute at that pressure under ideal in-home plumbing. Ella publishes no flow curve for lower pressures, so a home below 60 PSI should expect a slower fill rather than a failed one, and in real homes a fill runs about 7 to 15 minutes depending on the size of the tub and your supply lines. How fast will my walk-in tub fill? Fast-fill faucet expectations and operation sets out what the faucet can do, and this page explains where pressure fits among the other things that decide your fill time.

What the 60 PSI Rating Actually Promises

The rated flow figures are ceilings, not guarantees. They describe what the faucet passes when the house delivers 60 PSI through unrestricted plumbing, and the faucet is designed for unrestricted flow so it is rarely the reason a fill is slow. At about 16 gallons per minute, a tub with a capacity of around 60 gallons fills quickly rather than leaving you waiting, as Drainage and Fill Time notes. Lower household pressure means a slower fill, and since no figure is published for pressures below 60 PSI, the only honest way to know your real rate is to time a fill in your own bathroom. Draining does not depend on pressure at all, because the two 2-inch gravity drains typically empty the tub in two minutes or less when connected to a proper 2-inch drain line.

Pressure Is One of Four Things That Set Your Fill Time

Fill time is simply water capacity divided by real-world flow, and real-world flow is shaped by pressure, pipe size, the run from the heater and hot water use elsewhere. The capacity side is fixed by your model. You fill the tub after you are seated, so the occupied figure is the one that matters, and it is why fill times are shorter than the unoccupied capacity might suggest.

What the table means: two neighbors with the same faucet and the same pressure can see very different fill times simply because one owns a Standard and the other a Shak. If your pressure is on the low side, a larger tub feels it more, because the same shortfall in flow is multiplied over more gallons. Your exact model's numbers are on its spec sheet under the Downloads tab of the product page, and How long does it take to fill a walk-in tub? walks through the arithmetic.

How to Tell Whether Pressure Is Your Problem

1. Confirm both shutoff valves are fully open. They sit behind the access panel, and a valve that is only partly open is the most common and easiest fix for a slow fill.
2. Compare with another fixture. If pressure is low everywhere in the house, the fix is on the house side. If it is low only at the tub, look at the tub's own supply run, its shutoffs and any kink in the supply lines.
3. Note your supply line size. Existing 1/2 inch lines will work. Three quarter inch lines fill faster but are not required, and long runs of 1/2 inch house pipe feeding a faucet piped for 3/4 inch will hold the rate down.
4. Look for added valves. A thermostatic or pressure valve an installer added to the hot line can reduce flow and extend fill time.
5. On a thermostatic faucet, check for scale. Clogged TCV intake screens or the check valve at the bottom of the cartridge can choke flow to a trickle even when the water is hot. Your plumber can clean them with a soft brush and a lime scale remover.

Why Does My Walk-In Tub Fill So Slowly? goes through each of these in the order the team checks them.

Pressure Moves the Water, the Heater Decides the Temperature

Good pressure gets water into the tub quickly, but it says nothing about whether that water is hot for the whole fill. A 75 gallon or larger tank is recommended, and a tankless heater should be rated 11 gallons per minute or higher so it can keep pace with the faucet. The largest tubs, such as the ShaK and Big4Two, may call for a dedicated heater in addition to the one serving the house. Recommended Water Heater Size by Walk-In Tub Model lists the tier for each tub. The in-line heater on a hydro tub only maintains the bath temperature once the hydro pump runs, so a fill that arrives cool stays cool.

Planning the Plumbing Before Installation Day

• Ask your plumber to note the house pressure and to plan 3/4 inch water lines with easily accessible shutoff valves near the tub. Shutoff valves are not included.
• Both Ella fast-fill faucet sets include two 3/4 inch by 5 foot braided supply lines.
• Have the plumber weigh the distance from the water heater to the tub and any hot water use that will overlap with a bath.
• Ella's Bubbles does not send technicians, so this assessment is done by your own licensed plumber, and the team can answer questions for you or your plumber at ellasbubbles.com/support or (800) 480-6850.

If the shutoffs are open, pressure is fine elsewhere in the house and the tub still takes far longer than 15 minutes to fill, open a ticket with your serial number, a photo of the faucet set, a photo of the supply lines and shutoffs behind the access panel, your supply line size and whether any valve was added to the hot line.

Related Guides

• Water Supply Lines, Shut-Off Valves, and Pipe Size for a Fast Fill
• What Size Water Heater Do I Need for My Walk-in Tub?

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