Water damage can be expensive to fix, but if you can catch it early enough, you may be able to get away with minimal losses. Signs of leaks and water damage aren't always immediately visible but can be noticed by foul odors, discoloration, blistering walls and ceilings, or buckling floors. If you're lucky enough to catch the leak itself first, you can sometimes get away with drying the water out with little consequence. If you catch a leak after damage has already been done, you can at least stop the damage from getting too much worse.
Shut Off Leak
Before anything else, stop the source of the leak. Turn off your house's water supply to make any repairs; if it's something you can't fix, leave the water off until you can contact a plumber. After this, move any furniture and items out of rooms affected by water damage. This is both to help cleanup later and to help the water from damaging anything else in the meantime.
If you have enough water in your house to the point where it is collecting into puddles or certain areas, it needs to be removed. Don't wait to let it dry out by itself. This is especially the case for water collecting in your ceilings or on the floors. Water can be swept out the door if there isn't too much, or vacuumed up using a wet-dry vacuum. Be very thorough when searching for where the water may have gone. If the leak is one one place but the water puddled in another, it had to have gotten there somehow, which means possible damages in other places. Many cases, such as a flooded basement, warrant calling a professional to do water removal.
Dry Out Your House
Even if there is already damage, you don't want it getting any worse. It's also hard to start repairs while your house is wet, so it needs to be dried. In severe cases you may need to replace your floors, dry wall, and insulation, but this can sometimes be skipped if the problem was caught fast enough. For carpet damage, fold back the carpet from your walls and vacuum underneath it. When you have removed as much water as possible, set up fans and a dehumidifier in each affected room, then seal each room off with plastic in the doorways and windows. Also turn your heater on if you can. The combination of air flow, heat, and lack of humidity can dry much of the water and pull moisture from your walls and carpet.
If you see stains on your wall from water damage, this may actually be a good thing; if you can see stains, it means that your paint is porous. Porous paint breathes better and can dry out faster, which can mean you only need to repaint your walls instead of replace them.
Call For Mold Remediation
Even if you've removed all the water and everything looks fine, you need to call someone to inspect your home for mold. Mold starts growing in damp environments, but drying them out won't make the mold go away. Call someone as soon as you can to catch any mold growth before it becomes too serious.