The horizontal distance from the fixture outlet to the trap weir should not exceed how many inches?

The horizontal distance from the fixture outlet to the trap weir should not exceed 30 inches in order to properly maintain the function of the drainage system. This distance is important because if the trap is located too far from the fixture outlet, it could lead to issues such as a siphon effect or inadequate drainage. Keeping the distance within the specified limit helps ensure that the water seal in the trap remains intact, preventing sewer gases from entering the living space and ensuring efficient drainage.

Distances beyond this limit, such as 36 inches or 42 inches, could increase the likelihood of drainage problems and negatively impact the system's overall performance. Therefore, adhering to the 30-inch guideline is crucial for effective plumbing.