A slab leak is a serious plumbing issue that requires immediate attention, however, it’s common for them to go undetected for a long time. The water supply and sewage lines that run under the foundation are expected to last a long time, and though it depends on the material the pipes are made from, most homeowners get at least 20 years from their plumbing without significant issues. Some pipes, like those made from copper or brass, may last 50 or more years.

Every home and every plumbing system is different, and slab leaks may emerge well before the pipes are expected to need repairs or replacement. If any of the following are happening in your home, then a slab leak may be the culprit:

  • A water meter that won’t stop moving, even when everything is shut off. Your home’s water meter is sensitive enough to detect leaks when all other water-using appliances have been switched off. Shut everything down, wait a few minutes to ensure nothing is still using water (ice makers pull water on their own occasionally), and see if the meter is still going. If it is, then a slab leak may be present.
  • An unexplained loss of water pressure.
  • Parts of the floor are unusually warm, which could signify a leak in the hot water supply line. If you notice that the family pet has a new favorite spot to lie down, they may have pinpointed the leak for you.
  • Cracks or warping in the floor or walls. As water from the leak places pressure and seeps into the floor, it can cause floor and wall materials to shift and sustain damage.
  • Water appearing in unexpected places. Water always flows to the lowest spot, so if it penetrates through the slab, it will start pooling in the home. Look for puddles gathering around cabinets and in bathrooms.
  • Problems with mold and mildew. Water, especially if it’s contaminated, accelerates mold growth, so if parts of the floor or wall become mold hotspots, a leak is likely nearby. A common sign of mold and mildew is a musty smell, so use your nose if a leak is suspected.

If any of the above are present, contact a professional for an inspection. Ignoring a slab leak can be an expensive mistake.

What are the potential consequences of ignoring a water leak under the slab?

The longer it takes to repair a slab leak, the higher the chance that additional damage will occur to the home’s foundation. In many parts of Texas, including Houston, homes are built on foundations that rest on clay. When clay is exposed to water, it soaks it up and swells, causing it to shift and move. When the clay dries, it settles and moves again. If your home has a slab leak, then the clay-rich soil under the foundation will be swelling and shrinking constantly, which puts the entire foundation under a lot of stress.

If this stress is great enough, the foundation may split and cause the home’s floors and walls to crack and shift apart. If the situation gets to this point, repairs will likely be expensive, and it will be difficult to sell the home without first making those repairs.

What are some causes of slab leaks?

If the home’s plumbing is supposed to last for 20 or more years, why do some pipes fail well before then? There are several possible reasons, including:

  1. Installation mistakes – One of the most common reasons for slab leaks is improper pipe installation or handling. If the pipe is bent or dented during installation, this will be a weak point that flowing water will eventually push through.
  2. Expanding soil – Slab leaks can worsen foundation issues due to wetting the soil and causing it to expand. Leaks, though, may originate from poor water drainage from the home’s foundation, causing the foundation to shift and put additional pressure on plumbing, to the point that the pipe fails.
  3. Corrosion or abrasion – Inside the pipes, corrosion can cause a leak to spring if it progresses too far. Corrosion is more common when the home’s water is especially acidic or alkaline. Abrasion is also a concern for some pipes, because with time, if pipes rub up against soil, concrete or other pipes, it can cause enough wear to result in a leak. Hot water pipes are at an elevated risk of abrasion, as they expand while in use.

How can an experienced plumber help with a leak under a slab?

It’s impossible for a homeowner to resolve a slab leak without professional assistance. It may not even be possible to specify exactly where the leak is originating without an experienced plumber, as water can move in unpredictable ways once it escapes the pipe. Given the difficulties involved, here is why hiring a professional makes sense:

  1. They can find the leak – Experienced plumbers use sophisticated sonar-like technology to “listen” to where the leak is occurring. Even the minute sound of water trickling from a pipe is enough for sensitive instrumentation to pick up, and plumbers can use the technology to determine exactly where the leak is and how severe it is.
  2. They can determine its cause – A plumber can inspect the home’s pipes to determine their general condition, check water quality to detect possible corrosion and check for any installation mistakes that could have resulted in the leak. With this knowledge, it will be easier to avoid additional slab leaks in the future. 
  3. They can provide repairs – Repairing a slab leak is a real challenge and requires extreme care. Some foundations are built using high-tension cables that, if severed, can cause major damage to the home or serious injury to anyone nearby. Care is needed, and heavy equipment may also be needed. Plumbers may choose to access the leak by cutting and jackhammering through the floor, or by digging under the foundation and fixing the leak from below. In both cases, it’s a tough job that can only be managed by plumbers experienced in slab repair.

If caught and addressed early, an expert plumber may be able to avert additional damage to the home’s foundation. If left alone, though, it’s likely that foundation issues will worsen, which can cause structural issues and reduce your home’s value. It’s important to act quickly if there are signs of water damage or reduced water pressure.

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