Move items away from the wall as soon as you notice the leak. Remove hanging pictures from the wall and move furniture, including bookshelves and couches, away from the wall. If you have accent rugs close to the wall, move them away to prevent water damage.
Repair the leak. Whether the leak is caused by a burst pipe or extreme weather conditions, repair the leak as quickly as possible. Contact a plumber or general contractor if you don't feel comfortable repairing the leak yourself. It's important not to wait to fix the leak since the more time that passes, the greater your home's damage will be.
Clean the area around the leak. Use bleach or another household cleaner to disinfect your walls and flooring close the leak. Wipe down any furniture and spot clean any rugs in the area. Proper cleaning is important since damp conditions can accelerate mold growth in your home.
Run a dehumidifier in the room to reduce the amount of moisture in the air. Even after your leak is cleaned up, there can still be an excessive amount of humidity in the room. A small dehumidifier helps pull the excess water from the air and prevents mold and mildew growth due to the leak.