Locating a Foundation Leak in Your Basement

finished basement with carpeting floor and beige walls.
  • 1-3 hours
  • Beginner
  • 0-35
What You'll Need
Face mask and safety glasses (when looking for mold)
What You'll Need
Face mask and safety glasses (when looking for mold)

A foundation leak can be very troubling and stressful, which is why it is important to learn how to fix one. The first thing you must do when fixing any leak is identify the cause. The cause of foundation leaks can be of various sources.

It could be a result of a leaking water pipe, condensation, or simply because water is seeping from the surrounding ground. Whatever the problem is, you must identify the location and the cause of the leak.

WARNING: Some of the things you're looking for (such as mold) may be unhealthy to touch or breathe in, so have a face mask, safety glasses, and gloves handy while you're searching.

Finding Foundation Leaks

Examine the basement wall looking for any obvious signs of damage. Any cracks in the wall will allow water to enter. Cracks will normally be at the top or bottom of the wall. The cracks might be very small and difficult to spot, or they may be very noticeable. Use a flashlight to look for these cracks, as the light will make it much easier to find any cracks, no matter how small they are.


crack in concrete

There is a pretty simple test that you can do to determine whether the cause of the leak is due to water seepage or because of condensation. Tape a small square of foil to one of your walls. Leave it for a few days. When you remove the foil, the location of any moisture will allow you to make a determination.

Moisture on the front of the foil means that the problem is caused by condensation. Moisture on the inside of the foil means that the problem is from a leak. The only real way to deal with condensation is to use a dehumidifier to get remove all of the moisture form the room.

Looking for Deposits

Examine for signs of dampness or white deposits on your basement walls or foundation, which indicate a deposit which grows on concrete that alerts you to a leak. The crack or leak should be located very closely to this white deposit.

1. Paint

Paint will often peel when it gets damp. If there is any peeling paint in your basement, then that suggests that there has been or there is still a leak in the wall.

2. Mold

If there are any patches of mold or mildew on the ceiling, foundation, or basement walls, then there is moisture in the wall somewhere.

3. Floor Tiles

If there are any floor tiles which have started to raise or if there is any rust on the floor, then there is water in your basement.

4. Pipes

plumbing pipes

The cause of the leak could be your plumbing systems. Investigate the potential leaks to identify where it is occurring. The leaks often occur at joints, although the entire pipe could have frozen and burst. Alternatively, you might be suffering from the leak due to a continuously running toilet.


If you can't find the cause of the leak, then you should call in a professional to help you. Leaving it alone over the long term will only result in a more expensive repair some day down the road.