What it is
A spa, aka hot tub, is a vessel filled with heated water and used for soaking, hydrotherapy and relaxation. Typically, these portable units are made of acrylic, fiberglass or wood; there's also a vinyl version, called a soft-sided spa. which has a foam core or is a portable inflatable vessel. Spa features can include jets for massage and hydrotherapy, music and/or TV systems, fiberoptic lighting and more.
Another option for homeowners is the custom-built, concrete spa. Many who are having concrete inground swimming pools built on their properties include spas in the plans. The pool/spa combination is a popular choice.
If you count Mother Nature’s steaming mineral baths in Italy, the spa concept began 5,000 years ago. Many point to the ancient Egyptians’ use of public baths for therapeutic purposes around 2,000 B.C.
But for construction of an actual, albeit simple, spa, historians cite 600 B.C., when Phraortes, king of Media (a former empire in ancient Iran) had one constructed. The vessel was heated by super-hot stones.
Ancient Greeks delighted in building mineral and thermal baths, circa 500 B.C., but leave it to the Romans in the 300s B.C. to not only luxuriate in mineral waters, but also design huge public baths – the largest being the Diocletian at 130,000 square yards.
Two key European cities in such a history are Spa, Belgium, which has been famous for its medicinal spring waters since the Middle Ages, and Bath, England, where thousands flocked for healing purposes from 800 B.C. well into the 20th century.
In the United States, Native Americans were using natural hot springs for health and religious reasons long before Europeans arrived on the scene. In 1791, “floating swimming baths” appeared in Philadelphia; made of wood and canvas, these “therapeutic” vessels were either attached to the shore or the bottom of a lake or river. The first wooden hot tubs started appearing in the 1960s in California. To avoid the leakage problem from those early models, lightweight, acrylic portable spas were developed by various manufacturers.
The Jacuzzi spa was developed and patented by the Jacuzzi family in 1954. Some call it the first modern portable spa. Though many people use "Jacuzzi" as a synonym for “hot tub” or “spa,” it is a trademarked name and should not be used generically.
Hot tub – In the past, this term applied to a spa constructed of wood. Now it also can be used to refer to spa units formed of plastic, concrete, metal or other materials.
Hydrotherapy spa - A spa unit having a therapeutic use, but which is not drained, cleaned or refilled for each user. Includes, but is not limited to, hydrotherapy jet circulation, hot water, cold water mineral baths, air induction bubbles or any combination thereof. Industry terminology includes, but is not limited to, “therapeutic pool,” “hydrotherapy pool,” “whirlpool,” “hot spa,” etc. Industry standards exclude facilities under direct supervision and control of licensed medical personnel.
- Permanent Residential - A spa in which the water-heating and circulating equipment is not an integral part of the product. Intended as a permanent plumbing fixture and not intended to be moved (refer to ANSI/NSPI-3 Standard for Permanently Installed Residential Spas).
- Public - Any spa, other than a permanent residential spa or residential portable spa, intended to be used for bathing and operated by an owner, lessee, operator, licensee or concessionaire, regardless of whether a fee is charged for use (refer to ANSI/NSPI-2 Standard for Public Spas).
- Residential Portable Spa (two types) -
- Non-Self-Contained Spa - A spa in which the water-heating and water-circulating equipment is not an integral part of the product. Non-self-contained spas may employ separate components such as an individual filter, pump, heater and controls, or they may employ assembled combinations of various components (refer to ANSI/NSPI-6 Standard for Residential Portable Spas).
- Self-Contained Spa - A spa in which all control, water-heating and water-circulating equipment is an integral part of the product. Self-contained spas may be permanently wired or cord-connected.