Check your water meter, which is usually located in the front of the house. Note the number that the meter points to and wait 30 minutes. Do not use any water in this time. Check the meter when 30 minutes ends and if the numbers change, you probably have a leak somewhere and could have water damage.
Look around window frames and doors and where the ceiling meets an outdoor wall for discoloration. Do not forget to check the attic for discoloration, as well as the basement for water flowing through cracks in the foundation. These indicators could mean that water is coming from the outside of the house and finding its way in. Even a small amount of discoloration could mean a lot of damage within the walls.
Check all appliances for dripping and signs of water damage. This includes the toilet, sink, dishwasher and washing machine. This could suggest that you simply need a new washer or piping or that there is a larger problem in the system. Again, look for any discoloration as well as any dampness or softness on the floor or wall around these appliances.
Look for the more subtle signs of water damage, such as buckling of a wooden floor or peeling paint. Wood and paint will show the presence of water before other materials will.
Use your ears and nose to detect leaks. If you hear running water for no reason at night this could be a sign of leakage and water damage. Also, if you smell a musty or rank odor this is often a sign of mold, which indicates water and again, water damage.