A leaky pipe could be the culprit and if your basement is finished, you can’t see the pipes. Cutting a chunk of drywall out may have to be done to check the pipe behind it. Sometimes, it’s just a guess as to where to cut so you may have to try this more than once.
Surface water could be seeping into your basement. If the water is coming in only in a specific spot on an outside wall, it could be surface water from a lack of proper drainage. Make sure your gutters and downspouts aren’t clogged and that you have enough of them to move the water. The downspouts should extend 10 feet or more away from your house, without getting to close to your neighbor’s house of course. Another cause of excessive surface water could be that there are surfaces sloping toward your house. The ground around your house, and paved areas, should slope away from the house to keep the water from settling and pooling by your house. If you have an irrigation system, ensure it is not leaking or discharging too much water in one area.
If you are not seeing any sources of surface water, it could be under ground water. When water levels in the soil rise up above the level of the basement floor, water can seep into the basement through any cracks or holes because of the pressure, called hydrostatic pressure. Excess ground water can be caused by an lengthy rain storm, an underground spring or even the city’s storm sewer system, if a home’s drain system is connected. A perimeter drain might have to be installed to avoid under ground water seepage.
Water has also been known to come through floor drains in the basement as well. If that’s the case, it could be water backing up from the municipal sanitary sewer system. This would likely be a problem for older homes only as older plans combined sanitary and storm sewer systems. During a heavy rain, those systems could get overwhelmed which means water and sewage backing up. If this could apply to you, check into backflow preventers that can prevent water from coming through your drains.
To stay on the safe side, you might want to consult with a professional about preventing water in the basement. But if you do have the problem, whatever the source or cause of the water, contact either a plumber or a water loss mitigation company to address the issue and dry up the area. Then, contact your insurance agent to check on your homeowner’s coverage before filing a claim.