Bathrooms often share walls with other rooms — like closets, hallways, or adjacent bedrooms. It’s important to check the other side of the wall behind the shower or tub to look for signs of water damage. Water can migrate horizontally into adjoining spaces if there’s a leak in the plumbing, grout, or shower pan.

When inspecting the opposite side of a shared wall:

• Look for staining, bubbling, or peeling paint.
• Press gently on drywall to check for softness or crumbling.
• Pay attention to any musty odors coming from the wall or baseboards.

Also, pay attention to how high any staining or discoloration appears:

• Low staining (within 6–12 inches of the floor) often suggests a plumbing leak at the base of the shower, such as a failed shower pan, base grout, or a supply line leak.
• Mid-height staining (knee to waist height) may point to water leaking from a supply line running through the wall or a shower valve issue.
• High staining (shoulder height or above) can indicate issues higher in the shower wall, such as a cracked tile, failed grout line, or faulty shower head plumbing.

The higher and more irregular the staining, the more likely water is traveling through the wall cavity rather than simply leaking from the floor or base of the shower.

If you notice staining at the base of the wall, warped trim, or any sagging, it could indicate a leak that has been present for some time. If everything appears dry and intact, that’s a good sign you’re likely dealing with a minor surface issue.