Water Leaking Though a Concrete Slab

Concrete Slab Construction

• Concrete slabs are flat, level layers made of cement and aggregate mixed with water. The 4-inch-thick layer is poured onto a graded area over a layer of gravel and rolled to a smooth surface. Concrete slabs generally are installed over plumbing equipment. Careful investigation must be done to determine precisely where the leak is located to remove the proper section of concrete.

Causes of Leaks

• Leaks can be caused by the expansion and contraction of hot water pipes. Hard water also can cause leaks in plumbing beneath concrete slabs when it contains a high percentage corrosive chemicals such as iron, magnesium or calcium. These chemicals can deteriorate pipes over time, leading to cracks and holes. Detecting leaks under concrete slabs requires the use of special equipment, such as acoustic ultrasound or thermal imaging. Consult with a plumber or leak-detection service to determine exactly where the leak is occurring under the slab.

Signs of Concrete Slab Leaks

• Musty or moldy odors are a common signal that a leak problem has developed under the concrete slab. Water also might seeping up through the flooring. Low water pressure in the home or high water usage bills signal the possibility of a leak below the slab. Bad tasting water or dirty water also can indicate that you have a leak problem. Wall or ceiling issues also can be attributed to water leaks beneath the slab.

Repairing Concrete Slab Leaks

• A number of methods are used to repair leaks under concrete slabs. The traditional method is to track down the location of the leak and expose the pipe. The concrete is broken up in a small area to reach the leak and repair the pipe. The slab is then repaired with a patch. Another method uses cure-in-place pipe sealer to fix the leak without digging up the concrete surface.