Do walk-in tubs have heaters?

Many do — and if you like jets, you’re in luck

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bathtub being filled with hot water

Those with mobility issues or who simply want an easier and more spa-like bathing experience can benefit from a walk-in tub. Many of these luxury tubs also take away that annoying habit bathwater has of cooling down just when you start to relax, requiring you to add more hot water. That’s because they use in-line heaters to maintain the water temperature throughout your soak.

Key insights

An in-line heater maintains the water temperature in your bathtub for 30 minutes to an hour.

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In-line heaters only work when whirlpool jets are activated.

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These heaters can offset the capacity limits of smaller water heaters since you won’t have to refill your tub to bring the temperature back up.

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What are in-line heaters?

An in-line heater is an electric pump attached under your tub that automatically switches on when the whirlpool jets are activated. It suctions water from the bottom of the tub, pulls it through the pump’s heating element and is then returned on a continuous cycle as long as the jets are on. These heaters are not designed to heat up cold water, but they will maintain the temperature of hot water for 30 minutes to an hour.

Walk-in tubs with in-line heaters

In-line heaters come standard in walk-in tubs equipped with whirlpool features, so the real decision is whether you opt for a basic soaking tub or one with jets. Because the in-line heater relies on the continuous circulation of the jets, a basic soaking tub can’t make use of one.

Most walk-in tubs hold 50 to 80 gallons of water, which is also the size of a standard water heater, and a single fill can deplete your hot water reserves. The biggest benefit of the in-line heater is that it maintains the water temperature for up to an hour, so you can relax and bathe longer. If you only have a soaking tub, the water will cool down faster and the only way to bring the temperature back up is to add new hot water from the tap.

According to the representatives we spoke with, most homeowners won’t have to upgrade their water heater unless they’re purchasing a bariatric tub or if they live in a household with multiple people. However, one Kohler representative recommended upgrading to a higher-capacity water heater since many of their tubs can hold 95 gallons of water.

So, if you like soaking for a long time and are concerned about the water temperature dropping, consider opting for a jetted model to take advantage of the in-line heater. Additionally, if you have a smaller water heater, a tub with an in-line heater ensures the hot water you do have stays warm longer.

That said, if you plan to upgrade to a larger water heater when you install your tub, you may have enough to replenish the water when it cools down. Or, if you don’t like spending a lot of time in the bath or you’re on a budget, you could select a basic soaking tub without a heater.

Pros and cons of in-line heaters

Whenever you take on a home renovation like a walk-in tub, you should carefully weigh your costs and benefits. This is especially true when it comes to including deluxe features like whirlpool jets.


  • Maintains water temperature for up to an hour
  • Won’t have to refill tub halfway through if the water gets cold
  • Whirlpool jets provide therapeutic benefits


  • Tubs with whirlpool jets are more expensive
  • In-line heaters won’t heat up cold water

Cost of a walk-in tub with an in-line heater

Most walk-in tub manufacturers require an in-home consultation before they provide a quote. These are generally free, and most companies guarantee that the quote you receive during the consultation is the exact price you’ll pay. Because in-line heaters come standard with jetted tubs, the real cost differential is between a standard soaking tub and one with whirlpool jets.

Independent of installation charges, an entry-level soaker tub costs between $2,000 and $5,000, while tubs with whirlpool jets can cost as much as $10,000 or more, depending on the model.

» MORE: How to get financial assistance for walk-in tubs

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How do in-line heaters work?

In-line heaters suction water from the bottom of your tub, filter it through an external heating element, then redistribute the water back into the tub through a return.

Are there certain types of bathers that benefit more from in-line heaters than others?

All bathers can benefit from in-line heaters since they allow you to soak longer and enjoy the therapeutic benefits of massaging jets without worrying about the water cooling down.

Are certain in-line heaters more high-quality than others?

Although in-line heaters are made in different wattages, all the companies we spoke with reported their heaters were designed to maintain the water temperature within a couple of degrees for 30 minutes to an hour.

The only company we spoke with using a different model was Boca, which uses a friction heater to perform the same job. The company claims its friction heater is more efficient and can maintain the water temperature for over an hour, though it still requires the jets to be on.

Bottom line

Walk-in tubs offer more than just a safer bathing experience. If you’re interested in learning more, read about our picks for the best walk-in tubs to find one that fits your needs and your budget. Many of the best-reviewed models feature whirlpool jets with in-line heaters that can give you the spa-like benefits you’re looking for.

Article sources
ConsumerAffairs writers primarily rely on government data, industry experts and original research from other reputable publications to inform their work. Specific sources for this article include:
  1. Kohler Walk-In Bath, “Price Guide: How Much Do Walk-In Tubs Cost?” Accessed on May 23, 2024.
  2. U.S. Department of Energy, “Sizing a New Water Heater.” Accessed on May 23, 2024.
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