How to Check for Slab Leaks During Summer
- Local R&P
- 8 hours ago
- 5 min read
Slab leaks are among the most serious and expensive plumbing issues homeowners face. These leaks occur in the water lines running beneath the concrete foundation of your home—often going unnoticed until significant damage has already occurred. Summertime, with its higher water usage and shifting soil conditions, can increase the risk or visibility of slab leaks.
In this guide, we’ll walk you through the signs of a slab leak, why summer is a critical time for inspection, and step-by-step methods to detect leaks early. Whether you're a homeowner in San Jose or elsewhere, catching a slab leak early can save you thousands in repairs.
What Is a Slab Leak?
A slab leak refers to a water leak in a pipe located beneath a concrete slab foundation. Most often, the leak occurs in copper water lines that run beneath homes, especially in older properties built before the 1980s.
Slab leaks can be caused by:
Corrosion of pipes
Soil movement or foundation shifts
Abrasion from pipes rubbing against concrete
Improper installation or weakened joints
Left unchecked, a slab leak can lead to mold growth, warped flooring, foundation damage, and costly structural repairs.
Why Summer Is Prime Time for Slab Leaks
Summer brings unique environmental and usage conditions that make slab leaks more likely and easier to detect:
Increased water usage from lawn irrigation, showers, and appliances puts extra strain on plumbing.
Dry soil contracts, causing the foundation to shift and place stress on pipes.
High temperatures may cause pipe expansion and contraction, increasing the risk of joint failure.
Better ground visibility makes detecting moisture outside your home easier than during wetter seasons.
If you’ve noticed higher water bills or unexplained dampness in your home during summer, it’s time to check for slab leaks.
Common Signs of a Slab Leak
Before grabbing tools or calling a plumber, pay attention to these warning signs that indicate a possible slab leak:
1. Unexplained Increase in Water Bills
A sudden rise in your monthly water bill with no change in usage is often a red flag that water is leaking somewhere out of sight.
2. Hot Spots on the Floor
If a hot water line is leaking under the slab, you may feel warm areas under tile, carpet, or wood flooring.
3. Damp or Wet Floors
Persistent wet spots on your flooring or baseboards, especially without visible water sources, can indicate a leak under the slab.
4. Mold or Mildew Smells
Moisture trapped beneath flooring or in walls from a slab leak often results in musty odors or visible mold.
5. Cracks in Walls or Flooring
Uneven foundation settling caused by water erosion can result in small but noticeable cracks in your drywall, ceiling, or floor.
6. Low Water Pressure
If the water line under the slab is leaking, you may experience a noticeable drop in water pressure throughout the house.
7. Running Water Sounds
Hearing water running when no taps or appliances are on is a clear indicator of a hidden leak.
How to Check for Slab Leaks Yourself
While professional detection is highly recommended, there are a few steps you can take to investigate a possible slab leak before calling a plumber.
Step 1: Perform a Water Meter Test
What You Need: Screwdriver, flashlight, and access to your main water meter.
Shut off all water-using appliances and fixtures in your home (including ice makers, sprinklers, etc.).
Locate your water meter (usually near the curb).
Open the lid and observe the meter dial.
If the meter's leak detection dial (small triangle or gear) is spinning, you likely have a leak.
Wait 15–30 minutes and check the meter again to confirm movement.
If your meter continues to move while no water is being used, the leak may be under your slab.
Step 2: Conduct a Pressure Test
A drop in pressure is another indicator of a leak.
Attach a pressure gauge to an outdoor spigot.
Note the water pressure reading.
Shut off the main valve.
Check the pressure again after 15 minutes.
If the pressure drops significantly, you may have a leak within your plumbing system, possibly under the slab.
Step 3: Check for Hot Spots
Walk barefoot across tile or hardwood floors, paying attention to any unexpected warm areas. If you find a warm patch near the kitchen or bathroom, a hot water line may be leaking beneath the slab.
Step 4: Look Outside the Home
Sometimes the leak may show up as:
Pooled water near the foundation
Soil erosion around the home
A soggy lawn (especially near slab edges or where water lines enter the house)
Professional Slab Leak Detection
If your DIY checks point to a potential problem, it’s time to contact a licensed plumber. In San Jose and other urban areas, professional leak detection is typically done using one or more of the following methods:
1. Acoustic Listening Devices
These tools amplify the sound of water escaping from a pipe, helping pinpoint the leak’s location beneath the slab.
2. Infrared Thermal Imaging
A thermal camera can detect temperature changes on floors and walls, helping locate hot water leaks without destructive digging.
3. Pressure Testing with Isolated Lines
A plumber may isolate sections of the water system to test specific lines under the slab, narrowing down the exact location of the leak.
4. Camera Inspections
For sewer or drain line slab leaks, plumbers may insert a waterproof camera through access points to visually confirm cracks or breaks.
How to Prevent Slab Leaks in the Future
Once you’ve dealt with a slab leak—or if you want to avoid one altogether—there are several preventive strategies you can implement.
1. Use a Pressure Regulator
Excessively high water pressure can stress pipes. Keep household water pressure between 40–60 PSI to prevent joint failures.
2. Repipe Aging Plumbing
Older homes with galvanized or copper pipes are more prone to corrosion. Repiping with PEX or copper can prevent future leaks.
3. Monitor Soil Moisture
Use soaker hoses or sprinklers to maintain consistent soil moisture levels around your foundation during hot summers. This prevents uneven expansion and contraction of soil.
4. Schedule Annual Plumbing Inspections
Professional inspections catch early warning signs of corrosion, water pressure issues, or pipe wear before they become major problems.
Repairing a Slab Leak: What to Expect
Repair methods depend on the leak’s severity and location:
Spot Repair: Jackhammering the slab to repair the exact section of pipe.
Re-routing: Bypassing the leaking section by running new pipe through walls or ceilings.
Pipe Lining: Inserting a liner into the damaged pipe (less invasive, but limited to specific cases).
Repiping: Full replacement of old piping if the system is extensively damaged.
Costs range from $500 to over $5,000, depending on the repair method, labor, and location.
When to Call a Professional
If you notice more than one sign of a slab leak, or your meter test confirms a continuous leak, don’t wait. The longer you delay, the more damage is done beneath your home’s foundation.
Call a licensed plumber in your area immediately, ideally one who specializes in slab leak detection and repair. In San Jose, a licensed and bonded local expert can also help you comply with local building codes and permit requirements.
Conclusion: Stay Ahead of Summer Slab Leaks
Slab leaks are sneaky, costly, and often go undetected until real damage has occurred. During the summer months, extra water usage and dry soil conditions make it even more critical to stay vigilant. By understanding the signs, performing basic checks, and knowing when to call in a professional, you can safeguard your home against expensive repairs and water damage.
Remember: Early detection is key.
Need Slab Leak Detection in San Jose?
Call Local Rooter Plumbing at 408-868-8759 for fast, professional service. We specialize in slab leak detection, repair, and foundation-safe solutions. Serving San Jose and surrounding communities.
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