Which fixture is not required in each dwelling unit?

In residential plumbing, certain fixtures are deemed essential for a dwelling unit to ensure functionality, hygiene, and comfort. The kitchen sink, bathroom sink, and toilet are crucial for daily living and sanitation needs. These fixtures are typically required by building codes in every dwelling unit to facilitate the basic activities of cooking, personal hygiene, and waste disposal.

The laundry tub, on the other hand, is not universally mandated in all dwelling units. While it may be helpful for laundry tasks and cleaning, it is considered more of an amenity than a necessity. Different jurisdictions may have varying requirements regarding laundry facilities, and some may not include a dedicated laundry tub in their building codes for residential units. This illustrates why the presence of a laundry tub is not a requirement across all dwelling units, distinguishing it from the other fixtures listed, which are essential for general living conditions.