What are the common signs of a water leak under a bathtub and how can it be detected and repaired effectively?

Common signs of a water leak under a bathtub include water stains on the ceiling below, musty odors, and a noticeable decrease in water pressure. To detect a leak, you can check for pooling water, listen for dripping sounds, and inspect for any visible cracks or damage. To repair a water leak effectively, you may need to replace damaged pipes, seal cracks, or reseal the bathtub to prevent further leakage. It is recommended to consult a professional plumber for accurate detection and repair of water leaks.