To start, you need to pinpoint exactly where the water is coming from. This is easy to do if your basement wall is not finished and the cement wall is visible. But if you have a finished basement, then you need to investigate where the water is coming from. Is it actually coming from the wall or is it coming in from around the window or somewhere else?
Water coming from a window is a common problem in the springtime when the snow melts. Fixing this problem is as easy as caulking the outside window frame. Other times water can come in over the top of the foundation. Those cases are rare but patios that are built too high and rest above the foundation where it meets the brick line are usually the problem. Unfortunately, we only fix foundation problems.
There are two types of foundations that we waterproof: poured cement (concrete) and cinder block foundation. If water is coming from a cinder block foundation wall we will need to waterproof the exterior wall, which usually means excavating down to the footing and applying a waterproofing membrane (not to be confused with damp proofing; a spray application which is not recommended). Repairing a cinder block foundation from the inside usually is just a patch job and you should not attempt such a repair. Depending on the drainage system around the house, you might also require an exterior french drain.
If you have a poured foundation there are several places that it could leak from. The most common of those problems are foundation cracks and many times they are located at the corner of a window. Not all cracks leak but if you are getting water in your basement, the best course of action is to locate the original point where the water hits the floor, then determine if there is a crack in that area. If you have a finished basement you would have to go outside and inspect the foundation wall. All cracks, no matter what size, will show up on the outside of the wall. If there is parging on the exterior wall (the finishing cement that covers the poured foundation wall) then it can be a little tricky to locate the crack, especially if it is a hairline, but most times they will still be visible to the eye.
If you do not see a crack on the outside then there are other potential problems that may be causing water infiltration such as leaking form pins, honeycombing, seam leaks and inlet pipes to name a few. In all cases the first order of business is to determine where the water is coming from. If your basement wall is finished it may be required to open up the wall because if there is no evidence of a crack you can only guess where the water is coming from. To be sure that you actually have a foundation problem a hose test should be performed. Running a hose outside at the point where water is believed to be coming in, and letting the water run at that point, will show if the foundation is actually leaking, thereby eliminating any problems that exist above ground. If the test runs for 30 minutes and there are no signs of water, then you have to look elsewhere, possibly above ground in the bricks or even higher. Most of the time if it is a foundation problem there will be water after only a few minutes of running the hose.
A simple job can cost anywhere between $125 and $300, but the average repair costs range between $400 and $800, with increases depending on whether excavation is needed.