TL;DR: Wondering how to find a water leak underground? Hidden leaks can cause serious water damage, increase utility costs, and even threaten your home’s foundation. This guide explains how to identify the signs of an underground water leak, perform simple DIY tests, and know when it’s time to call a professional plumber.
- Learn the most common indoor and outdoor signs of an underground water leak
- Discover how to check your water meter to confirm hidden leaks and potential water main leaks
- Find out how high water bills, wet spots, and low water pressure can indicate trouble
- Follow two simple DIY tests for detecting water leaks underground
- Understand when professional leak detection is needed to prevent costly water damage
Think you have a water leak underground? If so, you don’t want to ignore it because a water leak can seriously damage your home and lead to costly repairs. In this blog, we’ll share some common signs of underground water leaks (both inside and outside). We’ll also share a couple of sure-fire tests to know if you have an underground/hidden leak.
Of course, the easiest way to find the source of a leak is to have a plumber find it for you. If you’d like us to assist with San Antonio water leak detection, call (210) 660-2424 or schedule an appointment online. Contact us today!
Signs inside your home that you have an underground water leak
If you notice the following signs, you might have a water leak underground in your home:
- Noticeable drop in water pressure when using plumbing appliances
- Hissing or splashing noises
- Dirty or rusty water (although this could be due to another problem)
- An increase of mold or water-loving insects in your home
- Sewage smell or moldy odors
- Unexpectedly high water bills that continue to increase month after month
- Warm or damp spots on floors that may indicate hidden leaks beneath the slab
What to do if you notice these signs: Reach out to a San Antonio plumber for help ASAP. If left unchecked, you could risk severe water damage to your home.
Signs outside of your home that you have a water leak underground
If you notice the following signs, you might have a water leak underground in the pipes outside your home:
- Wet spots in your lawn
- Potholes or sinkholes
- Sewage smells
- One area of your lawn that is unusually green compared to the rest of your lawn
- Cracking and breaking of paved areas (like a driveway or concrete slab)
- Flooded water around a sprinkler head or water spurts between sprinklers
- Steadily increasing water bill over the last few cycles (without any alteration in household water usage)
What to do if you notice these signs: Seek out professional water leak detection. Water leaks underground can seriously hurt your lawn and even potentially damage your home’s foundation.
Two DIY tests to help you know if (and where) you have a water leak
If you’ve noticed some of the signs we mentioned above and still want to verify you have a leak in your water line, we’ll share two easy ways to check.
1. How to test for a main water line leak
Follow these steps:
Step #1: Make sure no water is being used inside or outside your home (turn off all faucets).
Step #2: Locate your water meter (usually found in a box in front of your house near the street/sidewalk).
Step #3: Read your water meter. If you have a digital water meter, shine a light on the flow screen and see if it is flashing a number above zero. If it is, that means you have a leak. If you have an analog water meter, look for a small red triangular dial or a small silver wheel. If either one is moving, that indicates you have a leak.
Determine if the main water line leak inside or outside of your home
Step #1: Locate your home’s water shutoff valve. You’ll typically find this valve in a garage, basement or outside wall.
Step #2: Close the valve, which will shut off the water supply to your house.
Step #3: Go back to your water meter. If the leak indicator stops moving, then you have a leak inside the house. If the leak indicator continues to move, then the leak is outside between the meter and the house.
This is one of the most reliable ways to check for leaks and determine if you may have a water main leak between the meter and your home.
2. How to test for a sewer line leak
Best practices for detecting water leaks underground include these steps:
Step #1: Get any kind of dye (can be food dye, clothing dye, etc.)
Step #2: Pour a few ounces of the dye down the toilet and flush it a few times.
Step #3: After 30–60 minutes, go to the part of your yard where you think the leak is (where there’s a pool of water, or the grass is greener). If the dye shows up, you have a leaky sewer line.
Note: This test only works leaks in the outdoor sewer line, not for sewer line leaks inside your home. If you think you have a sewer line leak inside, you’ll need to have a plumber perform a camera inspection to find the source of the leak.
Want a licensed plumber in San Antonio to find and fix your water leak?
Call (210) 660-2424 today! We’ll quickly find the source of the leak and give you upfront prices on the cost to fix it. When you wonder how to tell if you have a water leak underground or how to find a water leak underground, remember the Shafer Family has been providing plumbing services in San Antonio since 1884!
Stop Plumbing Problems Before They Get Worse
We know how stressful plumbing issues can be. Leaks, clogs, or low water pressure never happen at a good time. Our expert plumbers make it simple. We diagnose the issue, explain your options clearly, and fix it right the first time.
No surprises. No pressure. Just reliable service you can trust.
Frequently Asked Questions
How can I tell if I have a water leak underground?
Common signs include unexplained high water bills, wet spots in your yard, reduced water pressure, mold growth, and the sound of running water when no fixtures are in use. Checking your water meter while all water is turned off can help confirm a leak.
What causes underground water pipe leaks?
Underground water pipe leaks can be caused by aging pipes, shifting soil, corrosion, tree root intrusion, poor installation, or excessive water pressure. Over time, even small weaknesses can develop into significant leaks.
Can a water main leak damage my home?
Yes. A water main leak can saturate the soil around your home, potentially causing foundation movement, cracked concrete, landscape damage, and expensive water damage if left untreated.
When should I call a plumber for leak detection?
You should call a plumber as soon as you notice signs of an underground water leak. Professional leak detection equipment can locate hidden leaks quickly and accurately, helping prevent larger repairs and unnecessary water waste.
