Al’s Plumbing, Heating & A/C Repairs Slab Leaks. 

Al’s Plumbing, Heating & A/C in Plano, Texas provides maintenance & repairs for all brands of Central A/C, Gas & Electric Furnace, and Heat Pumps.  Additionally we sell and install new HVAC Systems from American Standard (same company as Trane), Ameristar (same company as American Standard) and Coleman HVAC (same company as York HVAC).

Al’s also provides full service plumbing maintenance, repairs and replacements for every plumbing component in your home.  Al’s sells and installs Rheem Professional Series gas & electric water heaters, and tankless water heaters.  Al’s is near your home in Plano, Allen, Frisco, and McKinney.  We service all homes in southern Collin and Denton Counties with no additional travel-charges.

Call Al’s today to discuss any concerns or problems you have with your HVAC System or Plumbing.  We will arrange an appointment at your convenience and offer 24/7 Emergency Service

18 Signs You Have A Slab Leak


Learn How To Minimize The Risk Of Slab Leaks With Slab Watering (at the end of this article)

photo of underground water leak

Image Source: Flikr  Photographer: Scott Durnell

Shown: Large Under Slab Water Pipe Leak

A Slab Leak Is Typically Due To A Leaking Water Supply Pipe Under Your Home.

Your DFW Slab Home’s Water Pipes Are In The Soil Under Your Home. 


The Fastest & Easiest Way To Know If You Have A Slab Leak

  • Be Sure Every Water Outlet In The Home + Outside Faucets Are Turned Off.
  • Watch Water Meter To See If It’s Recording Water Usage.
  • Nearly All Water Meters Have A Rotating Gauge (may be an arrow or “gear”).  It Shows Even The Slightest Water Usage (see “gear” below).
  • If you see movement, watch to see if it continues for 1 minute. You could have a ice-maker filling with water.
  • If dial is moving (and all water sources are off) you have a slab leak.

water meter

Photo Source: Dreamstime ID: 00126239

For This Meter, The Black “Gear” Will Turn With Even The Slightest Water Usage


The Term Slab Leak Is Commonly Heard In DFW,  It can be caused by either a leaking Water-Supply Pipe, or a leaking Sewer Pipe under the home’s slab foundation.  This article addresses only leaking Water-Supply pipes.

Slab Leaks in DFW are common.  They are caused by the home’s slab foundation moving up & down with changes in soil moisture.  DFW is built upon Expansive Clay Soil. When the clay gets wet, it expands in size.  When the clay dries out, it shrinks.  The clay can dry out to the point is becomes dust.  The home’s slab foundation depends on support from the ground underneath it.  It order to ensure the soil provides consistent support, the moisture level in the soil must be kept stable. 

Click Below To See What Happens With Expansive-Clay Soil With Changes In Soil Moisture:  

Expansive Clay Soil — Wet & Dry

The soil moisture becomes more stable the closer you get to the center of the slab.  Along the edges and corners, the clay soil dries out easily, then rewets when it rains.  This causes the edges and corners of the slab to rise and fall.  Over time, this will likely damage the foundation and crack water supply pipes.   This problem can be minimized with “Slab Watering”.  This is providing a watering schedule to ensure the soil-moisture stays stable. 

Many homes with automatic lawn-sprinkling systems also provide slab watering.   The only way to know if yours does is to talk with the company who installed it, or have an inspection done by a service that installs and repairs automatic lawn watering systems.

For Homes without an automatic lawn watering system, the home must be surrounded with “Soakers Hoses” operated by timers (more on this later within this article).  The frequency and length of time slab watering must be done depends on the time of the year.  During the coldest part of winter, slab watering  is not likely needed.  During the hottest period of summer, it’s needed frequently.  Soil Moisture-Meters will advise the current level of soil moisture so the home owner can adjust the recurring watering schedule as needed.  Soil Moisture-Meters will give you immediate information on soil moisture level (more later within this article).

An Active Slab Leak Can Generate Enormous Water Bills

And May Damage The Foundation (As Soil Moisture Continues To Rise)

The most common type of slab leak is due a cracked or damaged Water-Supply Pipe.  As with most components within a home, Water-Supply Lines are subject to deterioration due to aging and can wear out or fail.

Often though, Water-Supply Line Slab Leaks are caused by a cracked water pipe due to Slab Movement in DFW area homes (due to DFW’s expansive-clay soil).

Your DFW area home typically has a concrete slab foundation.  Some homes are “Pier & Beam” which means the house sits upon piers driven into the ground deeply enough that they won’t rise or fall regardless of soil-moisture.   However, with Pier & Beam the soil can get so dry that the piers may shift (side to side) at the top.  Pier & Beam homes may require less watering, but they must be watered too.

Some Insight Into Water Pipes & Slab Foundations

And Explain Why Water & Sewer Pipes Crack Due To Slab Movement

1. During construction the Water Pipes & Sewer Pipes are put into place below ground level.

home slab foundation under constrction - water pipes showing(Photo Source: Dreamstime ID 98604079

Shown: Slab Foundation Under Construction.  Water Pipes Are Coming Upward From Slab (Inside Black Foam Wrap)

Click Here To See A More Detailed Photo: Sewer Pipes Installation For Slab Foundation Home

2. After the plumbing is installed, the next steps in creating a slab foundation take place.

Image Source: ShutterStock

Shown: This Is The Foundation Just Before Cement Is Poured.  In the photo you Can See Water Pipes (blue & red) And Sewer Pipes (white).


3. The final step in creating a slab foundation is pouring cement (once cement dries it becomes concrete).

Image Source: ShutterStock

Shown: This Is What The Foundation Looks Like After Cement Is Poured & Dries Into A Concrete Slab. 

What Exactly Is A Water Pioe Slab-Leak & Why Why Occur

Most water pipes are near the edges of the home.  As shown above, the concrete is stuck to the pipes where they rise through the slab.   If the slab is allowed to rise and fall, the slab moves the water pipes up & down too.  If the water pipes are metal, this movement may eventually cause a “stress-crack”.  It’s much like bending a paper clip back & forth — eventually the metal will fail.


  • Most newer homes have flexible water lines named PEX.  These lines are able to move (to some extent) with slab movement.
  • However, these homes’ sewer lines are rigid plastic (PVC) that will crack if enough slab movement continues to occur.

Shown: PEX Flexible Water Tubing


Shown: PVC Rigid Sewer Pipe

 Signs You May Have a Water-Supply Pipe Slab Leak

  • Water bill will suddenly rises or spikes.
  • Water pressure appears to have dropped.
  • Damp or molded carpet.
  • Recent cracking in hard tile flooring.
  • Bucked or cupped laminate or hardwood floors.

warped wood floor due to moisture

Photo Source: Dreamstime ID: 42657777

Shown:  Warped Wood Floor Due To Moisture Coming Through Slab from Slab Leak

  • Drywall Cracks caused by slab movement.

Click Here To See An Extreme Example Of Drywall Cracks:  Drywall Cracks

  • Interior doors that stop closing right, stick or bind.
  • A musty odor (it’s likely mold or mildew caused by excessive moisture).
  • There is a visibly damp area in the concrete floor.

damp concrete and molded drywall due to slab leak

Photo Source: Dreamstime ID 1130844

Shown: Damp Concrete Floor And Molded Drywall Due To Slab Leak

  • A puddle of water on the floor inside the home.
  • Water against an exterior wall outdoors

Click Here To See Water Outside A Home That Is Evidence Of  A Slab Leak:  Water Outside Home — Slab Leak

  • You might be able to hear water movement sounds or hissing.

If The Slab Leak Is On A Hot Water Line:

  • You suddenly start running out of hot water when consumption has not changed.
  • Water heater is running more than usual or always running.
  • Somewhat increased energy bills.
  • Warm spots in the floor.  These can be spotted with a thermal-image device.

Click Here To See A Thermal-Image Device Locating A Hot Water Pipe Slab Leak: 

Thermal-Image Device Shows Location Of Hot Water Supply Line Slab Leak

  • In winter, a cat or dog is spending time in a new location — they found the warm spot where a hot water pipe is leaking.


Slab Leaks Must Be Repaired To Prevent Slab Damage 

Water Pipe Slab Leaks are not something to be ignored, or left until a later time.  The water added under your DFW home (from the leak) will cause the expansive-clay soil under the house to increase in size.  As this occurs, the soil below your home will exert increasing upward pressure on the slab. Over time, the increasing upward pressure can heave the slab upward which will result in a crack.

The concrete is likely to crack along the heaved area.   It’s common that one side of the cracked slab will be higher than the other side.  The higher side is where the soil has expanded due to the slab leak.

cracked and heaved concrete

Photo Source: Dreamstime ID 63049019

Shown: Heaved and Cracked Concrete At The Location Of A Slab Leak

How Water-Supply Pipe Slab Leaks Are Repaired

Find The Leaking Water-Supply Pipe

Different plumbers will use difference methods to determine the presence and location of a slab leak

  • Electrical equipment sends a small current through water pipes and a “listening” device can locate where water is leaking.
  • Force air into your water-supply pipe to remove any remaining water.  Then only air is escaping through the crack in the pipe.
  • The location of the leaking pipe may be found by using a sensitive “listening” device.  It locates where air is flowing out of the break in the pipe.


There Are 2 Ways To Gain Access Under A Slab

Busting Through The Slab From Inside The House

hole cut through slab foundation

Image Source: Dreamstime ID 7780291

Show: A Hole Cut Through The Slab To Gain Access To The Leaking Water Pipe.

(The “Grid” You See Is The Steel Reinforcement Inside The Concrete)

A hole is cut through the slab from inside the house.  Jack-hammers break away the concrete and soil is set aside.  Once the work is done, the soil is returned and a cement patch is poured to seal the opening.

Problems With Busting Through A Slab

  • In most cases, residents must move out of the room, or the entire house.
  • If the work can be contained to one room, there are still times when a resident likely won’t want to be there, such as when jack-hammers are operating.
  • Glued down floor coverings are damaged or destroyed.
  • The home is exposed to any mold spores or gasses trapped under the slab.  For a sewer pipe slab leak, the home is exposed to bacteria and germs in sewage.
  • The Slab Was Designed & Built To Be 1 Piece.  It Was Never Intended To Be Cut.


Newer DFW Homes Have Post-Tension Cable Slabs.  Cutting Through A

Post-Tension Cable Can Cause Injuries & Requires Expensive Repairs

photo of post tension slab foundation before cement is poured

Image Source: Dreamstime 17314786

Shown:  This Post-Tension Slab (see criss-crossed cables) Is Ready For Cement To Be Poured


Post-Tension Slab Homes Have A Warning (often stamped into concrete) Never To Cut Or Drill

Click Here To See A Sample Warning Not To Cut A Post-Tension Slab: Post-Tension Slab Warning

Home Builders Stamp This Warning Into The Concrete So They Are Not Held Liable For:

  • Damage to the home’s interior if a cable is severed during a slab leak repair.
  • Possible slab foundation and home structural-integrity issues caused by a severed Post-Tension cable.
  • Injury or death that can occur when a cable is severed
  • If cutting through a post-tension slab, extreme care must be taken to avoid & not cut the high-tension cables inside the slab.
  • If a cable is severed, the cable retracts violently toward the center of the slab (the cable was stressed with tremendous outward-pressure).
  • Severed cables have been known to create damage inside the home during contraction.
  • There are also documented cases of injuries or death caused a violently contracting cable.

The Western Group, a company that performs post-tension tendon & concrete repairs, said “When a post-tension cable snaps or is cut, it’s like a .44 Magnum going off.  These tendons carry over 30,000 pounds per square inch (psi).

“Most plumbers don’t even know what a post-tension cable is,” says Tim Downs, technical training supervisor for American Leak Detection in Santa Ana, Calif. “They come in with their saws and start cutting.”  Downs himself once cut a post-tension cable several years ago. “The very first one that I ran across, I didn’t know what it was, and I  cut right through it.”

Dick Bonin, a marketing representative for The Western Group Bonin has seen the destruction in vivid detail. “I’ve looked at some pictures that would scare the hell out of you,” he says, “Where the cables have gone through the concrete and gone through walls and doors.”  Arnie Rodio, owner of Pacesetter Plumbing in Lancaster, Calif.  said “There’s a story about a cable bursting out of slab and slicing a guy’s foot off.”

 Read The Entire Article Here: “Defusing The Bomb”


Click Below To See How Extensive A Post-Tension Cable Can Become (scroll down for photos):

Extensive Repair Required For Damaged Post-Tension Cable

Tunneling Under The Slab From Outside The House

tunnel under home slab foundation

Image Source: Dreamstime 80454143-1

Shown:  Tunnels Dug Under The Home For Water & Sewer Pipe Repair Or Replacement

Benefits Of Tunneling Under The Slab

  • No Risk Of Cutting A Post-Tension Cable

  • Residents can typically live in the house while the work is being done.  All the work is outdoors and under the home.
  • No floor-coverings are destroyed.
  • The home is not exposed to anything toxic under the slab (such as mold or gasses).
  • The slab is never cut.  It remains in one piece, just as it was: designed, built, and intended to always be.

Why You Must Minimize Your Home’s Slab Foundation’s Movement

In Many Cases, A Slab Leak (Or Foundation Crack) Could Have Been Avoided If

The Soil Moisture-Level Around The Edges Of Home Had Been Kept Stable

Slab Watering Also Reduces The Risk Of Needing Foundation Repairs 

DFW is built on expansive-clay soil.  When the clay in the soil gets wet, it increases in size.  This creates an upward pressure underneath your home’s slab, causing the slab to move upward primarily along the edges and corners.  When the soil

  • When the soil is too wet, upward force occurs mostly along the edges & at the corners of the slab (caused by the soil around the edges of the house swelling due to moisture).
  • When the soil is too dry, the soil shrinks (it can turn into dust if it gets dry enough).
  • When the soil is too dry, there is insufficient support from the soil around the edges of the home, and the slab can experience uneven downward pressure (from the home’s weight).
  • The slab does not move evenly.   The movement is mostly at the edges and corners of the slab.  The slab moves very little at the center.

Click Below To See Images Of What Occurs With A Concrete Slab When Soil Moisture Is Not Maintained

Slab Bending Due To Drying & Wetting Of Expansive Soil

This occurs when the soil around the home becomes too wet and expands -or- becomes too dry and becomes smaller.  The closer to the center of the slab, the less the soil moisture-level varies.  Since the majority of the changes in moisture-level occur at the corners and outside edges of the slab, the slab’s movement is greater at the edges and corners.

Why slab movement can break water supply-lines or waste lines. The horizontal waste pipes are under the slab and run through the soil under the house.  The vertical pipes go up through the slab where they are connected to plumbing fixtures above the slab.  If the slab bends, it puts upward or downward pressure on the water & & sewer pipes.  Over time, they may crack and a slab leak occurs.

When the slab moves up or down (due to soil moisture-level changes):

  • The vertical pipes (attached to plumbing fixtures inside the home) move up and down with the slab.
  • The horizontal pipes don’t move (because they are located within soil).
  • If the slab movement is enough, the pipes can crack due to the upward or downward pressure the slab-movement creates on the pipes.  The older the pipes become, the more likely they are to fail under slab-movement pressure
  • NOTE: This same movement is also what creates the need for many foundation repairs in DFW..

How To Minimize Slab Movement / Bending

Due to Soil Moisture-Level Changes

Click Here To See A Diagram Of Slab Movement When Sitting On Expansive-Clay soil: Slab Movement Diagram

1. Install Gutters To Eliminate Water  Near The Edges Of The Foundation (minimizes large increases in soil moisture).

  • This is accomplished with Rain Gutters to catch and move the water away from the foundation.  Allowing rainwater to fall right at the foundation causes tremendous changes in soil moisture-level. The more the moisture-level changes, the more the slab moves.

brick home

Shown: A Home With Rain Gutters Installed.   You can see a gutter downspout (white vertical pipe left of garage door).


  • It’s equally important to install Gutter Downspout-Extensions to carry the water at least 3 feet away from the foundation.

Shown: Slip-On Gutter Downspout Extension

Click On Image To: View Product, See Details, or Purchase From


2. Provide “Foundation Watering” During Periods Of Hot & Dry Weather (to reduce large decreases in soil moisture-level). 

It’s important to “water” your DFW home’s foundation when the soil around the home is too dry (this is mostly during summer).   This reduces the chances of damage to the foundation and water supply lines & waste lines due to slab-movement caused by low soil-moisture around the edges of your home.   Many automatic irrigation (lawn sprinkling) systems are designed to water the foundation (if it was part of the original installation).


For Those Without An Automatic Lawn-Watering System

These 3 Items Can Create A Foundation-Watering System

  • SOAKER HOSE                                             

Click On Image To: View Product, See Details, or Purchase From


 Click On Image To: View Product, See Details, or Purchase From

Note: Timers For Multiple Hoses Are Also Available



  • SOIL MOISTURE METER                               

Other Important Things To Know

  • Most (if not all) municipalities allow foundation-watering at any time on any day.  Check your City’s website to ensure you are in compliance if foundation-watering restrictions apply.
  • The best time to water is at night as there is no sun, and cooler temps reduce the amount of evaporation.
  • Place soaker-hoses 18 inches away from the foundation.
  • Start by setting the water-timer for 2 hours each day.
  • Monitor soil moisture to determine if 2 hours is enough.
  • As the weather gets hotter & drier during the summer, you will need to increase the frequency and length of time that you water.



This article addresses slab leaks caused by a damaged water-supply pipe.  The two primary reasons a crack occurs in a water-supply pipe are 1. movement of the slab foundation and 2. pipes failing due to age.

The article also describes how water-supply pipes slab leaks are located and repaired.  Also, access to the pipes needing repair is discussed as 1: busting through the slab for access or 2: tunneling under the slab to gain access to the pipes where they are in need of repair or replacement.

Also discussed are Post-Tension Slabs.  This style of slab construction has been the standard in DFW for new homes built since the 198o’s.  Building a post-tension slab is not typically dictated by Building Code, rather a choice for home builders because they are less expensive to build and post-tension slab’s strength is notably increased due to the inward compression (in all four directions) of the cables inside the slab.

Post tensioning compresses concrete, helping it to resist both shrinkage cracks plus cracks caused by difficult soil conditions. Steel strands are run through the concrete in a grid pattern. Each strand is housed inside plastic tube that allows the steel cable to move during the stressing (tightening) operation.  The combination of the steel strand and anchorages is called a tendon. As each tendon is pulled tight, the steel stretches and is held in place by the anchorage on the outside edge of the slab.  The tight tendons help the slab resist forces that act to pull it apart.

Post tension slabs are not designed to be cut through.  If during the cutting a cable is cut, the results can be damaging to the slab, and the notable chance of bodily injury or death is present due to the violent contraction of the cable toward the outside edges of the slab.  Post-Tension Slab homes have a warning stamped into the concrete not to cut or drill into it.  It is possible to cut through a post-tension slab — by first locating the tendons and cutting between them.  The photo below shows and example of this being done successfully.

Lastly, the article details how to minimize slab movement due to changes in moisture level.  It’s a simple and tremendously important home-maintenance task for DFW area homes, due to DFW being built on expansive-clay soil.  This clay increases and decreases in size with changes in soil-moisture level.  This causes the slab to move up or down due to pressures created by the soil underneath the home.

DFW homes are built on what is called “floating slabs”.  These slabs are designed to accommodate minimal movement without damage.  The only water to minimize slab movement is to keep soil moisture levels consistent at the outside edges of the slab (moisture level stays increasing consistent father toward the center of the house).



Al’s Plumbing, Heating & A/C in Plano, Texas provides maintenance & repairs for all brands of Central A/C, Gas & Electric Furnace, and Heat Pumps.  Additionally we sell and install new HVAC Systems from American Standard (same company as Trane), Ameristar (same company as American Standard) and Coleman HVAC (same company as York HVAC).

Al’s also provides full service plumbing maintenance, repairs and replacements for every plumbing component in your home.  Al’s sells and installs Rheem Professional Series gas & electric water heaters, and tankless water heaters.  Al’s is near your home in Plano, Garland, Richardson & Rowlette.  We service all homes in southern Collin and Denton Counties with no additional travel-charges.

Call Al’s today to discuss any concerns or problems you have with your HVAC System or Plumbing.  We will arrange an appointment at your convenience and offer 24/7 Emergency Service