The shower riser is the water pipe that brings water up to the showerhead when the tap diverter is engaged to power the shower part of your tap system. The riser for most modern showers is encased inside the wall, which means you won't notice a leak directly. Instead, it's important to know the indirect signs of a shower riser leak so you can catch problems before they become too severe.
1. Loose Tiles
The tiling on the shower wall is often the first to show outward signs of a leak. As the wallboard becomes damp, the adhesive that holds tiles in place loosens. You may notice cracks in the grout around some of the tiles, or the tiles may actually begin falling off the wall. Sometimes the tiles most affected are those that are directly underneath the showerhead, which is the path the riser follows.
2. Peeling Caulk
Caulk is used throughout the shower. It seals the edges of tiles to the sides of the shower pan or tub, as well as seals the pan itself to wallboards or flooring. There is also likely caulk or gaskets that seal around the tap handles, faucet, and showerhead. Moisture in the walls from a leaking riser affects caulk much like tile adhesive. It causes it to loosen, crack, and peel. Gaps may begin to form as the caulk peels away.
3. Warped Flooring
Vinyl and linoleum flooring around the shower are most likely to show the signs of water damage as moisture from the leaking riser follows gravity and begins to pool beneath the shower pan. The flooring may peel up or warp, for example. It may also feel spongy when you walk on the flooring, thanks to moisture causing the wood subflooring to rot.
4. Water Stains
Water stains are typically only visible if the moisture seeps into the bare wallboard in the bathroom, which means it has spread beyond the tiled shower surround. If the bathroom is on the second floor, you may also notice water stains on the ceiling of the room directly beneath the shower. This is because water from the leaking riser flows downward.
5. Mold and Mildew
Finally, never ignore your nose. If you pick up the stale odor of mildew or mold in the bathroom, it could be due to a hidden leak. This is especially true if you are sure that all surfaces are clean and mildew-free.
If you suspect a leak in the water lines or shower riser pipe in your bathroom, call a plumber immediately.