Slab Leaks, Causes and Repairs

Slab construction became popular during the post-WWII construction boom because it was faster and cheaper. A rebar-reinforced thick concrete slab is poured directly onto a prepared surface. Plumbing lines run below this surface and, after set, are difficult to reach.

Over time, these plumbing joints might leak or crack, creating a slab leak. In the plumbing world, this is considered one of the most serious issues a property owner could face. As the water seeps out, it can erode the soil underneath the reinforced slab, removing solid support for the slab. This strain of uneven ground can cause cracks in the slab which can grow from a hairline crack to an inch or more. Once this happens, the water leaking from the pipes can enter straight into your house.

Primary Causes of Slab Leaks

1. Plumbing Materials

Slab leaks come from some failure in the plumbing system. For example –faulty installation, cheap materials, weakened water lines, or soil shifting beneath the slab. A problem with the pipes themselves could just be a result of when your foundation was built, no fault of your own, and likely something completely out of your control and the control of the previous homeowner. This type of problem is nearly impossible to predict ahead of time. 

2. Soil Shifts

The most common cause of slab leaks is soil shifts from expansive soils. The American Society of Civil Engineers says about 25% of all homes in the United States experience damage due to expansive soils. Soil shifts are found to be the most expensive, damaging and widespread problem for homeowners. 

Signs You May Have a Slab Leak

Slow leaks can go years without being detected. Changes can be so incremental they go unnoticed. It pays to investigate if you notice any of these signs of slab leaks

  • Higher water bills without increased personal usage
  • Sounds of running water
  • Foundation develops a crack
  • Damp places on floors
  • Bad smell from floors or walls
  • Appearance of mold or mildew
  • Uneven growth in lawn or foundation plants
  • Visible shift in the soil around the structure

If you have one or more of these in your home, contact a licensed plumber immediately for a consultation.

Options for Slab Leak Repairs

The age, materials, and condition of a home’s plumbing system will dictate whether the job calls for repairs or replacement of a section of plumbing or a complete re-piping of the plumbing system beneath a home.

Plumbers use three of the four most widely recommended methods to repair slab leaks, including pipe re-routing, tunneling, and, when necessary, breaking through the concrete slab from the top. We make our recommendation after carefully studying the job and any complicating factors.

Pipe Rerouting

Sometimes, it makes sense to avoid digging altogether and reroute plumbing above ground. For example, if a short section of pipe is the problem and it can be worked around by installing new plumbing lines, rerouting may provide a quicker and less disruptive solution.

In some cases, such as when a home’s plumbing lines are encased in concrete and cannot be reached without destroying the slab, it may be best to re-pipe the whole house. Water supply lines can be routed around the slab instead of beneath it. The plumber will determine where new pipes can be installed.

Breaking Through the Slab

The shortest distance to the source of the problem may be straight down through the concrete slab, but that also may be the most disruptive and most expensive. Because of this, we cut through the slab when other options are not available or are less attractive for some reason. There is no one-size-fits-all solution.

Tunneling Beneath the Slab

In our experience tunneling beneath the slab offers a number of benefits for homeowners:

  • You can stay at home while work is in progress.
  • The mess is kept outside of your home.
  • It’s often the least expensive choice.

Most homeowners prefer tunneling if they have expensive flooring. Some of the flooring would be destroyed by breaking through the slab from the top.

Trenchless Pipe Repair

Pipelining has become a popular option for many homeowners because it involves no trenching and very little digging to gain access to the problem area. The concept is simple: broken water lines can be repaired by lining the inside of a broken pile with an epoxy coating that dries and hardens to form a new pipe.

Pipe bursting is sometimes used to replace badly damaged water lines. This is also a trenchless solution. A larger pipe is fitted around the damaged pipe with a “bursting head.” When this head is pushed through, it destroys the existing pipe and replaces it. 

Slab Leak Prevention Tips

  1. Keep the soil around your house moist year-round.
  2. Be careful what you put down the drain. 
  3. Test the pH of your water. 
  4. Check your home’s water pressure.
  5. Get annual plumbing inspections. 

If you suspect a slab leak in your home, contact a plumbing service immediately. Our licensed and insured professionals can help decide the best course of action to resolve the problem without causing further damage to your home. Visit us at or call  (858)-365-8070.

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