A woman relaxing in a wooden hot tub.

10 Different Types of Hot Tubs

A woman relaxing in a wooden hot tub.

I love hot tubs. They don’t always love me back.

I’ve sat down on hot tub benches that had to have been designed for the Jolly Green Giant.

I’ve plunged into hot tubs that were ice cold. And more than once I have had to push flower petals aside that were the result of placing the hot tub too close to a beautiful background of bougainvilleas.

If you are reading this article before buying a hot tub, congratulations! You can avoid some of the mistakes I and my friends have made. Let’s get started with some basic definitions of hot tubs.

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Portable, In-Ground, or Spa?

There are two kinds of hot tubs, portable and in-ground. In the industry, there’s also a market segment for spas. The term “hot tub” has come to mean a “tub of water that is (comfortably) hot,” so you may need some more precise definitions when you are out shopping.

  • A hot tub is usually a wooden vessel made of redwood, cedar, or other natural materials. The hot tub is filled with water. It is serviced by heaters, air blowers, pumps, and other standard equipment. Hot tubs can be built to accommodate as many as 10 people, but they are usually built for no more than four people at a time and contain no more than 1500 gallons (5.7 cubic meters) of water. By this definition, every hot tub is above-ground.
  • A spa is a pool of water that is agitated by the action of jets or by bubbles introduced into the water. Spas can be larger than hot tubs, up to 3300 gallons (11.4 cubic meters). A spa can be installed above-ground, like a hot tub, as a self-contained unit usually consisting of a fiberglass tub, pumps, air blowers, filters, motors, and controls.
  • A portable spa, also known as a portable hot tub, is any spa that can be easily packed up and transported to a different location. There are soft-sided, lightweight, portable spas that can fit in the back of a car, but there are also “portable” hot tubs that weigh as much as 1,000 pounds (450 kilos).

You can spend from $500 to $50,000 and even more on a new hot tub, spa, or portable hot tub/spa. In-ground installation is always more expensive than above-ground alternatives, and only above-ground units are portable (or available at lower prices when used). And there are so many possibilities for materials that choosing the right hot tub or spa for your home takes a little homework.

Materials Make a Big Difference

Just about every waterproof material has been used by someone to build a spa. Manufacturers are constantly using new materials in new designs to build hot tubs and spas that are more comfortable, more durable, and more cost-effective than ever before. Let’s take a look at the materials you may encounter in your planning for the perfect hot tub or spa.

Chances are that you are already familiar with concrete and plaster. These materials are used to make the overwhelming majority of swimming pools. So, what is the difference between a swimming pool made with concrete and plaster and a spa or hot tub constructed from the same materials?

Spas take up less space than pools. They are less expensive to build than pools. They are easier to maintain and cost less to operate. And hot tubs are smaller and less expensive than spas. But no matter whether you are getting a swimming pool, a spa, or an in-ground hot tub, there’s a good chance that you will need some space away from the water for your equipment to operate unobtrusively, and the plumbing will be laid underground. Keep in mind that pipes underground cost more to repair when they fail.

Fiberglass and Acrylic

Vanity Art 59 Inch Freestanding Acrylic Bathtub Modern Stand Alone Soaking Bathtub with Polished Chrome UPC Certified Slotted Overflow and Pop-up Drain VA6610-S
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Fiberglass is the material of choice when there is a specific design requirement. If you want heart-shaped hot tub, or a spa in an interesting geometric shape, you can have it fabricated with fiberglass (at considerable expense). Sheets of fiberglass provide strength, and the application of a resin provides stiffness. The final coating of fiberglass, known as the gel coat, makes it impervious to chemicals you add prevent microbial growth.

An acrylic hot tub is basically a big glass bowl. Like a fiberglass hot tub, it can be set into the ground, set on a stand above ground, or placed on pedestals and enclosed by a deck. There are self-contained acrylic hot tubs that only require water and a 30-amp circuit to plug in equipment. These self-contained units are technically portable, but the weight of the tub, even when drained, is about the same as a grand piano.

Soft-Sided

Bestway SaluSpa Miami Inflatable Hot Tub, 4-Person AirJet Spa
Click image for more info

If you are discouraged from acquiring a portable hot tub because of weight consider a lightweight, very portable, also-self-contained soft-sided model. A soft-sided spa or hot tub is made of stiff but flexible foam rubber on an aluminum frame. The interior of the hot tub is lined with a waterproof cloth so it can hold water. The pumps and other equipment for the hot tub (or spa) are also covered with foam rubber to reduce noise. Soft-sided hot tubs are portable and inexpensive enough that even people who live in apartments may enjoy them.

Wood

A wooden hot tub with a wooden stairs on the side.

Chances are that you have seen many fiberglass hot tubs and spas enclosed in wood for aesthetic purposes, but it is also possible to make a hot tub or spa entirely out of wood. Many people prefer a hot tub made of the birch wood as used in a European sauna or redwood American-style. Wooden hot tubs are beautiful, but they require a lot of maintenance, they aren’t portable, and it is unusual for them to last even 20 years.

Vinyl-Lined Aluminum Shell

A Vinyl-Lined Aluminum Shell hot tub in the backyard.

A vinyl-lined aluminum is basically a small above-ground swimming pool with heat and bubbles. The aluminum shell provides the structure for the hot tub, and the vinyl liner makes it waterproof. The tub is then surrounded with a cabinet made of wood or other aesthetically pleasing materials.

Stainless Steel

ASTM International, and organization formerly known as the American Society for Testing and Materials, estimates that a stainless steel hot tub will not need any maintenance, provided it is not filled with salt water, for at least 50 years. Stainless steel is elegant and durable, and it’s even possible to find stainless steel hot tubs and spas that are portable. But they are very expensive and require specially trained welders and technicians for repairs and maintenance.

Jetted Bathtubs

A close look at a corner hot tub with jets.

If you don’t have room for a hot tub, consider getting a jetted bathtub. As the name implies, a jetted bathtub is a standard bathtub fitted with a pump and jets to create bubbles. Jetted bathtubs are usually designed to accommodate two people and are often round rather than rectangular. Because a jetted bathtub is connected to the same plumbing as the rest of the house, no additional heating or water treatment is required. Jetted bathtubs do not require skimmers, filters, or strainer baskets.

All the Rest

Just about any waterproof container can be and has been used as a hot tub. There are examples of hot tubs made from cattle watering troughs, rain barrels, and cisterns. But if you aren’t living off the grid, you probably will prefer your next hot tub or spa to be made from one of the materials we have discussed above.

Choosing the Right Hot Tub

Now that you know the kinds of hot tubs and spas on the market, how do you choose the right hot tub for your home? The four things you need to consider are the location, the shell, the plumbing, and the cost.

Location

An outdoor hot tub placed strategically for the sweeping view of the mountains.

Location is the first consideration in choosing a hot tub.

Where do you plan to place your hot tub? If it will be set in your garden or among the trees, you may prefer a natural look with a wood tub or an acrylic hot tub with a wood enclosure.

What will support your tub? You may need to opt for an in-ground tub if your deck cannot support the weight of the hot tub you want.

The kind of weather you experience in your location also influences your choice of hot tub. If you have cold winters, you may want an in-ground hot tub to prevent damage to plumbing. If you live in a windy desert location, you may want a hot tub or a spa that can be covered to prevent evaporation or mud accumulations after dust storms. If you live in a hot climate, you may want to place your hot tub or spa under an awning or under shade for use when outdoor temperatures are already hot.

And you change residences frequently, your first choice may be a portable tub.

Shell

The question you need to ask yourself when you are choosing the shell for your hot tub or spa is how many people will be using it at one time. Hot tubs are sold to accommodate two people, four people, and so on, up to ten people. When you take a look at models with lounges or molded seating, you can quickly get a good idea of how many people will fit in the tub.

Be sure you consider the overall use of the hot tub, not just party use. Consider whether you really want the additional outlay upfront for a hot tub that holds ten people that you use once or twice a year, when you only need seating for one or two on a regular basis. Your financial investment in your hot tub isn’t just its initial cost and any carrying charges if you buy it on credit. It is also the cost of power, cleaning, repairs, and liability insurance.

It is important to know how you intend to use your hot tub. Benches are fine for seating people for socializing, but you may want lounges if your main use of your hot tub is for a therapeutic soak.

And don’t forget to take a test soak before you buy. I have a friend who is unusually short. She bought a beautiful wooden hot tub with benches and had it delivered and outfitted with plumbing before she ever tried it out. She stepped in, sat down, and discovered she was in water up to her eyeballs. (She bought a booster chair and joked about using her tub au naturelle except for a floatation device.)

Plumbing

A hot tub placed on an elevated wooden deck with a view of the surrounding woods.

There are also important considerations in choosing the plumbing for the shell of your hot tub. It’s not hard to find a shell that has already been plumbed to meet the needs of an “average” user. Usually there will be two jets for water circulation for each person expected to use the tub. These jets will be set at varying heights. There will probably also be a bubble ring to create a massaging effect with turbulent water.

If you have personal preferences about the number, type, or location of these jets, say, if you happen to be 4’1” or 7’2” or you could be described as wide-bodied, then it makes more sense to have a shell custom-fitted to your specifications. Your dealer may be able to offer larger massage jets, or smaller “pinpoint” jets, or jets that can be turned on or off to create more pressure in a specific part of the tub or spa.

Some hot tub owners are only interested in the general turbulence of the water and want a hot tub with a water ring but no massage jets. Some hot tub owners are only interested in the water’s massaging action and only want massage jets but don’t care about the water ring. And some hot tub owners want a blower to “turbocharge” the massage jets. Take time to think about what you want in your hot tub or spa and talk to multiple dealers to make sure you are getting the hot tub or spa that best fits the bill.

Here’s an additional word of caution about pre-installed plumbing: Be aware that fixtures can snap off or out of place during transportation and delivery. Don’t by a hot tub or spa that has already been plumbed unless you are sure it can be delivered without snapping off or cracking exposed fittings and plumbing. Be sure the truck is big enough to haul the hot tub safely and the delivery company is providing you with enough workers.

Cost

Finally, just about everyone is concerned about cost. If you aren’t particular about appearances, you may be able to buy a used hot tub for as little as $500, but most hot tubs cost in the thousands of dollars. Be aware that you can spent 10 times as much for custom-built spa.

But don’t cut your costs too low. Make sure you get a pump that provides adequate water pressure. The rule of thumb is that every jet requires ¼ horsepower from the pump. You aren’t really saving money if you buy a unit with a less expensive pump that doesn’t have the power you need to really enjoy your spa.

Don’t skimp on filters. If you plan to use your hot tub or spa frequently, you may want a filter that is larger than specified to reduce costly annual tear-down and maintenance.

And spend a few extra bucks on timers. Having a heater that turns itself on an hour or two before you come on and want to use your spa can save thousands of dollars in gas or electricity costs over the lifetime of your hot tub or spa. It’s OK to use an electric water heater for a small hot tub, but larger hot tubs and spas should be heated with natural gas.

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