Why Is the Basement Leaking From the Floor?

It can be disconcerting to see water start to pool up on a basement floor without any direct cause like a flood or a burst pipe. The issue is not uncommon, especially in areas where houses were built at low elevations in areas with high water tables. Correcting the issue is not a simple process, but it is a necessity. Otherwise the water will slowly destroy the foundation.

Damp concrete is a strong sign of hydrostatic pressure problems.

Hydrostatic Pressure

When water appears to be coming out of the basement floor, the most likely cause is hydrostatic pressure. This happens when the water level in the ground -- the water table -- rises higher than the bottom of the basement. The water pressure underneath the basement pushes the water up through even the smallest cracks in the foundation. Even without the presence of cracks, the pressure can force the water through porous materials, like concrete, where it then pools on the basement floor.

Other Leaking Reasons

Hydrostatic pressure may be the main reason that water comes up through the basement, but there could be a few additional explanations. If there is a perimeter drain system around the foundation that connects directly to the sewer system, excess storm water could actually back up through the sewer system and leak into the basement. Similarly, if water is backing up through the regular sewer system into your house, the first place it will come out would be the taps and drains in the basement. Finally, before any corrective work is done, always ensure that the water isn't coming from a source inside the basement, like a leaky pipe or down the basement walls from a leak in the roof.

Correcting the Problem Outside the Basement

The way to correct a basement flooding problem outside the basement will depend on the topography of the area around the house. If possible, slope the land around the house away from the house in all directions. Also, replace any sandy soil with clay, which will be much more likely to dispel water rather than absorb it. If the house is near a hill or any other area that produces a large amount of runoff, create a French drain around the perimeter of the foundation. Ensure that the bottom of the drain is below the bottom of the foundation so the water is forced into the drain before it is forced into the basement. Without a direct source of runoff, this trench is best dug right next to the foundation, with the drain being installed right next to the footers.

Correcting the Problem Inside the Basement

To correct drainage issues inside a basement, the basement floor will have to be dug up a bit. Remove a 1-foot section from around the perimeter of the concrete block and replace it with gravel. Remove the rubble, dig a small ditch and install drain tiles. Slope the ditches to one corner of the basement where a deep sump basket is installed. Place a sump pump inside the basket where it can pump water outside of the house. Once everything is in place, a new cement floor is added above the drainage system.