A deep bathtub has a number of advantages over a typical a shallow tub. The main selling point of such tubs is probably the unparalleled capacity for relaxation that they offer, but they can also have therapeutic value for people with a variety of joint and muscle injuries. They also minimize the risk of spilling and overflow during the course of a bath. Deep tubs do have some disadvantages, however, including increased water-use, inconvenience for use as showers, and added expense.
The primary purpose of a deep bathtub is to allow the whole body to be submerged without the need for bending or contortion. A bath in a soaking tub, as deep tubs are sometimes known, can be tremendously relaxing. A normal tub works well for ordinary bathing but does not offer the same opportunity to luxuriate and relax that a deep bathtub can provide.
Relaxation in a bath of hot water is pleasant and can be very helpful for people in high-stress situations or lifestyles. Soaking in a hot bath has medicinal benefits as well and can relieve aches and pains in stiff muscles or swollen joints. Such relief is primarily palliative but can also have medical value as part of the treatment of minor injuries.
A purely practical benefit of a deep bathtub is the reduced likelihood of overflow or spill. Typical bathtubs are perfectly adequate for ordinary bathing. Parents bathing small children, however, may find that having a deep bathtub makes the process easier, and reduces damage to the rest of the bathroom.
Deep tubs are luxury items, and, as such, do add to the price of a bathroom. A typical deep bathtub costs more than a shallow tub, but the cost is not prohibitive for an ordinary homeowner. Luxury deep tubs can cost much more, however.
A deep tub uses more water than a shallow tub. Water remains relatively inexpensive in most communities, but the increased water consumption associated with a deep bathtub may discourage buyers who are interested in keeping their homes as green as possible. The additional water used by a deep tub must be heated, and this adds a small amount to both the operating cost and the environmental impact of a deep tub.
Homeowners who use their bathtubs primarily for showering may also not wish to purchase a deep tub. These tubs, while excellent for taking relaxing soaking baths, can make showering quite awkward. Many homeowners who choose to install a deep tub avoid this issue by adding a dedicated shower, but this entails additional expense and requires extra space.