How much water is needed for a stall shower test?

In a stall shower test, the goal is to assess the water-tightness and drainage efficiency of the shower installation. Filling the shower with water to within 1 inch of the top of the dam allows for a sufficient volume that can reveal any leaks or drainage issues without overflowing the shower structure. This specified water level helps ensure that the test is effective while also avoiding unnecessary spillage that might complicate the assessment of the shower's integrity.

Filling to full capacity may not be necessary and could lead to overflow, which may create confusion regarding the source of any water issues observed. Similarly, only covering the shower floor does not provide enough water to properly evaluate drainage and potential leak points, while filling 3 inches above the base may be excessive for a preliminary inspection. Thus, achieving a balance by filling to within 1 inch of the top of the dam is the most appropriate method for conducting a thorough stall shower test.