This article comes from The Spruce.

Comparing a Hot Tub and Spa

Like a spa, a hot tub has built-in jets to provide warmth, relaxation, and a massage-effect on people’s muscles and joints. Both are used for therapeutic reasons and socialization. In the early days—the late 1960s and early 1970s—hot tubs were made from wood, including cedar, redwood, cypress, teak, or a composite. In the mid-1970s, the technologically advanced portable acrylic spas were introduced, replacing the wooden tubs in popularity.

Hot Tub, Spa, or Something Else?

Today, the terms hot tub and spa are used interchangeably. Let’s throw in another one: jacuzzi.

Although it’s a company that has been around since the 1950s, when it started making pumps that could be submerged in bathtubs, people often use the word to describe a spa or hot tub, even if it’s another brand. All describe a large tub that is used for relaxation, hydrotherapy, warmth, and entertaining. All are equipped with built-in jets for targeting bathers’ sore muscles.

Basically, there are two types of hot tubs and spas: portable and custom-built or in-ground. Portable models can accommodate anywhere from two to eight or more adults. They can be inflatable latex or vinyl, which are usually less expensive; fiberglass; acrylic; polyethylene; or another type of plastic. Some hot tubs are built in traditional wood or even out of recycled materials, such as metal bins or barrels.

In-ground or custom styles are usually referred to as spas.

They can be attached or adjacent to an in-ground swimming pool and are often placed near each other as a warm-water-and-cold-plunge-type of therapeutic experience. Others are stand-alone hot tubs but set into the ground or custom-built. Some are sturdy portable models (not inflatable) from top manufacturers that are installed to look like they are custom-built in-ground models that can be positioned upon a raised platform, sometimes under a pergola or a gazebo. Others actually are custom-built and constructed of the same materials that pools are made of, such as concrete, fiberglass, or gunite, along with stainless steel, tile, or copper.

The word spa is often associated with a health resort where people stay overnight or longer. Spas or day spas are also commercial establishments where patrons receive aesthetic services, such as deep-tissue massages, facials, manicures, pedicures, body wraps, salt glows, and other pampering treatments.

The term hot tub is more specific in describing that tub with many strategically placed massaging jets and has experienced a resurgence in usage to distinguish it from a day spa.

Small hot tubs that accommodate two adults and are designed for a more intimate experience measure about three to four feet high by five feet across and hold approximately 500 gallons of water. Larger hot tubs measure around four to five feet high and six feet or more in diameter and are built to accommodate up to eight adults or more. They hold about 850 gallons of water.

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