What is the difference in drainage Fixture Units between a bathtub with an overhead shower and a bathtub with whirlpool attachments?

The distinction in drainage Fixture Units between a bathtub with an overhead shower and a bathtub equipped with whirlpool attachments lies in how these fixtures are evaluated for their drainage capacity and water usage.

In general plumbing practice, a standard bathtub with an overhead shower typically has a set drainage Fixture Unit value based on its design and expected water flow rate. In contrast, a bathtub with whirlpool attachments may have a different unit value because it includes jets and additional plumbing configurations that can affect drainage.

However, in this specific case, the functionality of both bathtubs leads to the conclusion that they require the same amount of drainage Fixture Units. This means that despite the added complexity of whirlpool features, the overall drainage requirement does not increase when compared with the overhead shower setup. As a result, the difference in drainage Fixture Units between these two types of bathtubs is zero, indicating that each is calculated to demand the same drainage capacity under typical usage scenarios.