How to Choose a Hot Tub

Hot tubs are sold on two numbers: the top temperature and the seat count. Nearly every portable tub reaches 104°F, and nearly every one claims six adults. Neither tells you what living with the tub is like.

Heating Rate — The number that decides daily life is how fast the heater warms the water. Portable tubs run on household power with modest heaters, and the good makers publish the rate. Across the portable tubs we carry, every one uses a 1,350-watt heater, and the published rates run from 1.5 to 3.0°F per hour.

Fill a tub with 60°F water from a hose and set it to 104°F. That is a 44-degree rise. At 3°F an hour it takes about 15 hours. At 1.5°F an hour it takes about 29. In practice, a fresh fill is a next-day soak, and the same is true every time you drain and refill. Cold weather and a missing cover make it slower still.

That is not a flaw. It is how portable tubs work, and it is why most owners keep the water warm between uses and why a good insulated cover matters as much as the heater. But plan for it.

Seat Count — "Up to six adults" usually means six people sitting upright, close together, in a tub about 5 to 6 feet across. Fewer is comfortable. Check the interior dimensions and the water capacity, not the number.

Wood-Fired Is Different — A wood-fired tub has a stove in the water and no electric heater. The one we carry takes a couple of hours from lighting to soaking and needs no electricity at all. The trade is that there is no thermostat: you manage the temperature by how much wood you burn.

Portable tubs come in four builds, and each trades something.

Insulation — How well the shell holds heat decides how much you spend keeping the water warm. One foam-panel tub we carry uses 10 centimeter panels, which its maker says hold heat far better than a standard inflatable. Ask each seller how the walls and floor are insulated.

The Liner — The liner is what holds the water, and it has the shortest warranty. On the portable tubs we carry, liners are covered for 6 to 12 months while frames on the rigid models are covered for 24. Ask what the liner is made of, and how punctures are repaired.

Listings love jet counts: 120 jets, 138 jets. The number is real and it is also misleading, because there are two very different kinds.

Air Bubbling Jets — Small holes, usually around the floor, that blow air up through the water. They are the source of those big counts. You feel an all-over fizz rather than pressure on any one spot, and every seat gets the same effect.

Hydro-Massage Jets — Water jets driven by a pump, aimed at your back and shoulders. They give focused pressure, and they come in far smaller numbers. On the rigid-frame tubs we carry, it is four jet sets with eight adjustable nozzles each, alongside 120 to 130 bubbling jets.

A tub with 138 air jets and no hydro-massage jets is a bubble tub, and a good one can be exactly what you want. But it is not the same product as a tub with 30-odd water jets, and the bigger number belongs to the bubble tub.

Noise — Air blowers and pumps make noise. If the tub sits near a bedroom window or a neighbor's fence, ask how loud it runs.

Filled Weight — Water weighs about 8.3 pounds a gallon. The portable tubs we carry hold 224 to 256 gallons, and one publishes its filled weight: about 2,105 pounds, before anyone climbs in. That load goes onto a small footprint. A concrete pad or level ground is simplest. A deck needs to be rated for it, so check before you fill.

Power — The portable electric tubs we carry all run on a standard 110 to 120V household supply. Ask whether the plug has built-in ground-fault protection, and whether the outlet you plan to use is on a circuit with room to spare. A wood-fired tub needs no power, but its chimney stands about 110 inches tall, so check overhead clearance.

The Cover — An insulated cover holds heat, keeps debris out and, with a lock, keeps children out. Check one is in the box rather than sold separately.

Water Care — Look for continuous filtration, and ask what sanitation runs automatically. UV sanitizers and ozone generators are common on the tubs we carry, and some combine both. You will still test and balance the water yourself and drain and refill it periodically, so ask the maker's recommended schedule.

Winter — Some portable tubs include freeze protection that keeps water from icing inside the pump. That is not the same as being built for year-round outdoor use in a hard winter. Ask what the maker allows in your climate, and how to drain and store the tub if not.

Local Rules — Some towns and most homeowners' associations have rules about hot tubs, and about open-flame appliances and chimneys for wood-fired ones. A phone call before you order is cheaper than finding out after delivery.

Delivery — Portable tubs ship by carrier and are light enough empty for two people to move, from about 55 pounds for an inflatable up to about 240 for a rigid frame. Wood-fired tubs ship by freight in a crate. On the tubs we carry, the carrier schedules delivery directly with you.

Returns — This is the trap in this category. Once a hot tub has been opened or filled, it usually cannot be returned. On the tubs we carry, returns must be unopened and unused, requested within 14 days, with a restocking fee and return shipping at your cost. That means you cannot try the tub and send it back. Be sure before you open the box.

The Warranty's Fine Print — Read four things:

1. 01Each Part Separately — Liner, frame and electrical parts often carry different terms. On the tubs we carry: 6 to 12 months on the liner, 12 months on the electrics, 24 months on rigid frames.
2. 02Registration and Proof — Keep your proof of purchase and note the serial number. Register the tub after delivery.
3. 03Maintenance — Improper maintenance is a standard exclusion. Keep a log of water care.
4. 04First Owner Only — Many tub warranties end if you sell the tub.

This section matters more for hot tubs than almost any other category, because so many are bought for short-term rentals. On every portable tub we carry, commercial or rental use voids the warranty entirely. A tub bought for a rental listing and used by guests is, for warranty purposes, not a home tub.

A rental or business tub runs hotter and longer, serves strangers, and gets far less careful handling than one in a family's backyard. So the first question is whether the maker offers a model warrantied for commercial or rental use, in writing. If not, budget for every repair yourself.

After that:

• Sanitation for Guests — Water shared by a new group every few days needs a stricter routine than a household tub. Plan who tests and treats it between stays, and keep a log.
• Local Rules — A tub used by paying guests or the public can fall under local health rules for pools and spas, and some rental platforms and insurers set their own. Check all three before you list it.
• Rules and Signage — Post clear instructions on temperature, time limits and the cover lock, and follow the maker's safety warnings. Guests will not read a manual.
• Durability — A liner that lasts years in a careful household may not last a season of guests. Price in replacement liners and covers.
• Service — Ask who repairs the tub in your area and how fast. A broken tub at a rental is a refund conversation.