Homeowner reported a water stain on the ceiling of the powder bathroom located beneath the master bathroom. An access opening was cut at the stained area, and no plumbing leaks were found. A second access opening was created below the master bathroom shower pan for further investigation. The shower was tested by plugging the drain and filling the shower pan with water. Testing confirmed that neither the shower pan nor the shower drain connected to the shower pan was leaking. Further investigation determined that water was escaping the shower due to a shower curtain that was too short, allowing water to exit the shower, saturate the vinyl flooring, and leak through the subfloor.