Plumbing Repair Under Slab: 3 Warning Signs You Might Need It

High water bills could be a sign of needing plumbing repair under slab.

If you’re like everyone else you know, you probably spend an inordinate portion of your day pondering the intricacies of slab leak diagnosis and location. Or to put it another way … what are the warning signs of needing plumbing repair under the slab? And how do you find the location of the leak?

Well, anticipate no longer, folks. I am about to demystify slab leaks for you!

There are a handful of things that make our customers start to wonder whether or not they might have a slab leak.

The most common include the following:

1. A month on month comparison of water bills shows a significant increase in water usage from that shown on the last statement. If you can’t think of any reason for this increase (It’s summer now and you have been replacing evaporated pool water, lawn irrigation, etc.), you may have a water leak.

If your floor is strangely warm in only one spot, you may have a slab leak.

2. If you walk through your home with bare feet, you notice that there is one area on the floor that is consistently warmer than the other areas, you may have a water leak.

If your water heater can't keep up, better call Gary's Quality Plumbing.

3. If your water heater is fired up seemingly always and you still can’t seem to get a hot shower even though you live alone in a house with two or three 50-gallon water heaters, you may have a water leak.

If any of these conditions sound familiar to you, give Gary’s Quality Plumbing a call at 972-424-6479.

Here is what the leak location process will look like.

A pressure gauge helps determine the location of a slab leak.One of our Master Plumbers will ensure that you have no obvious fixture leaks (dripping faucets, toilets that run, etc.). Then we install a pressure gauge on one of your fixture supplies. A hose-bib or the washing machine supply valve are common spots to do this.

Once the working pressure of your water supply/distribution system has been noted, we shut the water off at the meter near the street.

If the pressure reading on the gauge stays where it started for 15-20 minutes, it is a safe assumption that you simply used more water that month. This is the point where customers will remember that they had family in town and the number of daily showers in the house quadrupled for a week. Mystery solved. Tragedy averted.

If the pressure drops, we attempt to determine if the water being lost is hot or cold. This is accomplished by shutting the supply to the water heater off.

If the pressure holds at this point, we know that you have a hot water leak somewhere. But, if the pressure continues to drop. you have a cold water leak.

Now if its a hot water leak, we know it’s inside of the house. But if cold, we have to isolate the house water supply from the yard line.

This is done by shutting the water off at the valve in the flower bed near the house. If the pressure in the home remains constant after shutting off that valve, you’re in luck. The leak is in the yard somewhere.

If the pressure continues to drop, you have a cold water slab leak.

Where exactly is that under slab plumbing repair needed?

Once we have accumulated all of this information, we follow a very specific methodology for determining where exactly where the leak is located. It goes something like this:

  1. We transmit a signal at a specific frequency down the water pipe.
  2. Using a wand-like tool, we can locate that exact frequency under the slab.
  3. Using blue painters tape, we mark all of the sub-slab water pipe on the floor. Now we know where all if the water pipe is.
  4. We pressurize the system with compressed air.
  5. We follow the marks we made with the tape from one end to the other with a highly sensitive directional set of headphones.

There is a microphone for each ear allowing us to tell which direction the sound of the air escaping is coming from until we end up right on top of the problem.

Gary’s Quality Plumbing Excels at Under Slab Plumbing Repairs

This process takes years to master and requires a great deal of skill and accuracy. This only comes with doing a thing over and over for years. It is also one of our specialties here at Gary’s Quality Plumbing. We do this better than anyone else! And have a stunningly pristine record for coming down right on top of these leaks when through-slab work is required.

The process detailed above works for both hot and cold water leaks. However, in the event of a hot water leak, we can employ a third tactic which increases accuracy even further.

Using a laser thermometer, we can use the other two pieces of information (where there is pipe and where the leak makes the most noise) and add a third. The hot spot.

Wherever there is pipe, it is noisiest, and if it’s also the hottest spot on the floor, we’ve found the slab leak. Every time.

If you enjoyed learning about the process of locating water leaks below a slab foundation, stay tuned. Subscribe to our newsletter and we’ll send it direct to your email – along with other helpful plumbing tips (and special offers on rare occasions).

My next article will outline the exciting process of repairing these types of leaks.

No spoilers, but it doesn’t have to be as messy as your friends and neighbors’ horror stories make it seem!

Danny Skinner, Master Plumber at Gary's Quality Plumbing in Plano, TX.

Article by Danny Skinner, M41026, a Registered Master Plumber by Texas State Board of Plumbing Examiners, a family member and plumber on the Gary’s Quality Plumbing team. 

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