Identifying where your water leak is coming from is key to repairing the problem and avoiding structural damage and mold growth. You can perform a capillary test to determine if you have a leak inside your wall. Dry an area of the wall where there is moisture. Cover the dried area with a large sheet of plastic and seal the edges to the wall with tape. Leave undisturbed for two days, then check the underside of the plastic for signs of moisture.
If the underside of plastic is beaded with moisture, then you have a water leak in your interior wall. If the underside of plastic is dry, but moisture is present on the room side of the plastic then condensation is the most likely cause of excess moisture. When both sides of the plastic are wet, then you have a combination of room condensation along with a leak in your interior wall.
When you have water leaking through your walls and into your home, structural damage to your home may occur. Water stains your drywall, making it look brown or yellow. Drywall may begin to crumble or tear when soaked with moisture, as well. When water is present on your walls, ceilings or flooring mold can grow. Mold damages the material it is growing on and can cause people in the home to develop symptoms associated with mold exposure, like persistent wheezing, shortness of breath, and nasal congestion.
When you have a water leak inside your interior walls, call a plumber for repair. Check around the perimeter of your home for places where water can seep inside, as well. Homes with inadequate foundation drainage often have standing water indoors after heavy rainfall. Keep your downspouts free from debris to avoid clogging and place extensions on your downspouts to carry water further away from your home. Inspect your roof for missing or damaged shingles that may allow water to seep inside and run down your walls.
When mold growth is visible inside your home, clean it up to avoid health problems and costly repairs. Remove mold by scrubbing it away with a brush dipped in liquid dish detergent and water. Once all mold is gone, rinse with clear water and dry the area thoroughly. An area of mold growth larger than 25 square feet is best handled by a mold-removal specialist.