A walk-in tub is worth it for a bather who cannot safely step over a tub wall and will use the seat and door. It also needs a taller drain setup, a sealed door, water heater capacity, and often dedicated 120-volt circuits. Grab bars or a low-threshold shower may meet the same need.
How does a walk-in tub work day to day?
A walk-in tub has a watertight door in the side. You step in while the tub is empty, sit on the built-in seat, close the door, and then the tub fills. The American Bath Group instructions are firm on the order of steps: never begin filling the tub with the door open, and the bather should be seated inside with the door latched shut before filling. When you are done, the tub has to drain before the door can be opened. The same instructions say to always drain the tub before opening the door, to enter and exit only through the door while the tub is empty, and never to climb over the side.
That design is the point of the product, and it is also its main trade-off. You wait, seated and wet, while the tub fills, and you wait again for it to drain. Kohler's FAQ says fill and drain times may vary depending on the water pipe capacity and flow rate of your home's plumbing, and it offers a heated backrest and a handshower to help you stay warm while the tub fills. So the wait is partly about the pipes in your house.
The ABG instructions add two more points a buyer should know:
- Soaking temperature. The maximum soaking temperature should not exceed 104 degrees F, and the instructions say to consult a physician about temperature and length of use for your health situation.
- Supervision. Children and elderly or infirm bathers must remain under close supervision.
What does the plumbing side need?
A walk-in tub is taller than the tub it replaces, so the plumbing has to change to match.
Supply lines. The ABG installation steps say you may be able to reuse the existing water supply lines, but that they may need to be extended to meet the higher than typical tub. Drain. The same steps say to relocate the drain line as required for connection to the overflow kit provided with the unit. The instructions also give a minimum tub height to ensure proper drain installation, measured from the top of the tub flange to the floor, and tell the installer to adjust the leveling feet to reach it.
Faucet. ABG notes that its walk-in tub does not include a tub filler, and suggests considering a high flow rate faucet so the tub fills faster. It also suggests a faucet mixer with thermal protection to prevent accidental scalding. A faster fill shortens the seated wait, but it depends on what your supply lines can deliver.
Water heater. Kohler says its walk-in bath is designed for use with standard residential water heaters, and that, depending on your location, a 40, 50 or 75 gallon water heater can be sufficient. It says the dealer reviews the age, condition and volume of your water heater during the quote and decides whether it is adequate. Our page on what size water heater you need explains how to think about capacity, and why you may run out of hot water in a shower shows what a heater that is too small looks like.
Grab bars and a handheld shower. ABG says to plan and install water supplies and reinforcement for grab bar mounting before you install the tub. The wall has to be built for that, so decide before the tub goes in.
Testing. After installation, the instructions say to fill the tub with the door latched, watch every fitting for leaks, shut the water off at about three quarters full, and recheck that the tub is level.
What does the electrical side need?
Not every walk-in tub has electrical parts. The ABG instructions say that if the tub has an air system or a whirlpool system, electrical power supplies must be provided, each component needs a separate, dedicated circuit, and all wiring must be done by a qualified electrician. The circuit requirement it lists is 120 volts, 60 hertz and 15 amps, protected by a Class A ground fault circuit interrupter connected at the main electrical service panel for each component. The dedicated circuits end in grounded receptacles in water resistant enclosures, set at least 6 inches above the subfloor and hidden from view when the job is done. The instructions call for access to the electrical parts, either through a removable panel or a removable section of the wall board, and to test the GFCI periodically.
Tubs with an air system also run a drying cycle after draining. ABG says the injector motor runs for about 30 seconds after the tub is drained to push out water that seeped into the air bubblers, and that the cycle should not be interrupted. Tubs with water jets only do not have it.
Do you need a permit, and who installs it?
Kohler says a local authorized dealer installs its walk-in bath in as little as one day, and that you do not need to hire a plumber. That describes Kohler's dealer program, not your city's permit rules. In Phoenix, the plumbing permit exemptions cover clearing stoppages, repairing leaks, and replacing valves or fixtures with compliant new ones, but the city says a permit is required to relocate any valves, pipes or fixtures. A tub that changes the drain position or the supply heights is closer to relocation than to a like-for-like swap. Our page on whether you need a permit to remodel a bathroom in Phoenix explains the test. Ask whoever sells the tub who pulls the permit, and get the answer in writing. Other Valley cities have their own rules, so check with yours.
Kohler also says a walk-in bath already installed cannot be retrofitted with its shower package, because the dealer cannot perform the extensive plumbing and electrical work needed later. If you might want a handshower or shower package, decide before the install.
When is a walk-in tub the right answer, and when is it not?
The strongest case is a person who has trouble lifting a leg over a tub wall and who enjoys a seated soak. The CDC's fall prevention advice for older adults lists making your home safer, including adding grab bars inside and outside your tub or shower. That is a smaller change than replacing a tub, and it can be done on its own or alongside a new tub.
A walk-in tub is a weaker fit in these cases:
- The person bathes mainly by showering. A shower with a low entry may be the better change. Our page on what is involved in converting a tub to a shower covers the plumbing, and the minimum shower size by code covers the size limits.
- The wait bothers them. Sitting through the fill and the drain is part of every bath.
- The water heater is small or old. A tub that holds a lot of water depends on the heater to keep up.
- Hot water is slow to arrive. A long pipe run also lengthens the fill.
Ask a plumber to look at the bathroom before you sign an order. The questions are whether the supply lines and the water heater can serve the tub, where the drain can go, how the floor and framing will carry the load, and who handles the permit and the electrical circuits.
HQ Plumbing and Air is licensed and insured, takes emergency calls 24/7, and gives free estimates with an upfront price before work starts. See our plumbing services.