Modern bathtubs have overflow and waste drains and may have taps mounted on them. They may be built-in or free standing or sometimes sunken. Until recently, most bathtubs were roughly rectangular in shape but with the advent of acrylic thermoformed baths, more shapes are becoming available. Bathtubs are commonly white in colour although many other colours can be found. The process for enamelling cast iron bathtubs was invented by the Scottish born American David Dunbar Buick.

Two main styles of bathtub are common:

• Western-style bathtubs in which the bather lies down. These baths are typically shallow and long.
• Eastern style bathtubs in which the bather sits up. These are known as ofuro in Japan and are typically short and deep.

Tub bathing

Soap and bath salts may be used when bathing. A bath is often used as a technique to temporarily relieve body aches and pain.

Clawfoot tub

The clawfoot tub or claw-foot tub is typically made of cast iron, or sometimes acrylic. Once considered a luxury item, modern technology has contributed to a drop in the price of clawfoot tubs. Hence, while true antique clawfoot tubs are still considered collectible items, new reproduction clawfoot tubs are chosen by remodellers and new home builders.

Clawfoot tubs come in 5 major styles:

• Classic Roll Rim, Roll Top, or Flat Rim tubs as seen in the picture above.
• Slipper tubs - where one end is raised and sloped creating a more comfortable lounging position.
• Double Slipper Tubs - where both ends are raised and sloped.
• Double Ended Tubs - where both ends of the tub are rounded. Notice how one end of the classic tub is rounded and one is fairly flat.
• Pedestal Tub - Pedestal tubs, unlike all the styles listed above, do not have claw feet. The tub rests on a pedestal in what most would term an art deco style. Evidence of pedestal tubs dates back to the Isle of Crete in 1000 BC.

Baby bathtub

A baby bathtub is one used for bathing infants, especially those not yet old enough to sit up on their own. These can be either a small, stand-alone bath that is filled with water from another source, or a device for supporting the baby that is placed in a standard bathtub. Both types are designed to allow the baby to recline while keeping its head out of the water; however, the baby must always be supported by an adult as well.

Hot tubs and whirlpool tubs

Hot tubs, spa pools are common heated pools used for relaxation and sometimes for therapy. The "hippie" era (1950 - 1970) popularized them in America in songs and movies. A spa is also called a "jacuzzi" in USA since the word became a generic after plumbing component manufacturer Jacuzzi introduced the "Spa Whirlpool" in 1968.

Air bubbles may be introduced into the nozzles via an air-bleed venturi pump that combines cooler air with the incoming heated water to cool the pool if temperature rises uncomfortably high. Some spas have a constant stream of bubbles fed via the seating area of the pool, or a footwell area. This is more common as a temperature control device where the heated water comes from a natural (uncontrolled heat) geothermal source, rather than artificially heated. Water temperature is usually very warm to hot — 38°C to 42°C (100 to 104 °F). So bathers usually spend a short time inside, 20 to 30 minutes at 39°C. Bromine or mineral sanitizers are often recommended as sanitizers for spas because chlorine dissipates at a high temperature thereby heightening its strong chemical smell. Ozone is an effective bactericide and is commonly included in the circulation system with cartridge filtration, but not with sand media filtration due to clogging problems with turbid body fats.