How to tell if you have a water leak underground or inside a wall (Do This NOW!)

No matter how careful we are about water in our homes, leaks can still happen. A leaky pipe might not be too noticeable and could go unnoticed for a long time.

The best way to determine whether you have a water leak underground is to check the pressure of your pipes or check the water meter. If the pressure is low, that means there’s something wrong with your water supply. Plumbers have special tools to detect underground water leaks. Let’s study some more alternatives.


What are some signs of a water leak underground or in a wall?

If there’s a leak in your home, you might see the following signs:

1. A drop in water pressure. If the pressure is low, that means there’s something wrong with your water supply.

2. A discolored or wet spot near the leak. Tiles can also break or sink around this area.

3. A musty smell or you hear water running

4. Mold growth around the leak

Example of a water damaged floor. Image by PlumbingInstantFix. All rights reserved.

5. A higher water bill. A lot of houses are getting a digital water meter, making it easier to detect leaks. You can also install a system on your pipes that measures the usage and water pressure and alerts you when it drops, indicating a potential leak. 

6. The water meter keeps turning, even when all the faucets and devices that use water are off. The water meter is often found outside or in the garage. It is possible that your system doesn’t have this meter installed and that a plumber has to do this for you.

7. The city might notify you that the water usage is higher than usual

8.A circuit breaker might trip. Be careful when this happens as water and electricity don’t go well together and you might get a shock.

9. You hear water running or see a wet spot.

Leaks behind a wall or under the ground are hard to detect and require more work to locate.

Sometimes you have to break the floor open to examine things further. Image by Plumbinginstantfix. All rights reserved.

How to locate a leak behind a wall

To further isolate the location of the leak, you can close valves on your system and see if the water meter keeps running. For example, yopu can shut off the warm water and see if this affects the water meter or not. This allows you to get closer to the problem.

More recently there are also sensors (such as Moen and Energizer) that measure the humidity in a room and can alert you if there is a potential leak. Finding the exact spot might require the help of a plumber as leaks can be really small or hidden behind a wall.

Small stains on the wall can indicate problems so make sure to investigate them.

Plumbers have special tools to detect leaks behind a wall

– A  water detector can be used as well. This device has two electrodes connected to a battery. One electrode can detect water while the other is connected to the ground. With these two sensors, plumbers can locate leaks and patch them quickly. Using your hands can also be a great tool. Feel on walls and floors to see if they feel moist. This can indicate that the leak is close by.

– A heat camera can work as well as water cools down certain areas. Not every plumber is specialized in this though so you might have to ask if they have experience with finding leaks when you call one. This is part art and part science as there are a lot of things going on in a house and isolating the signal of a leaking pipe can be a challenge.

– This is often done by using a listening tool. This can be compared to a stethoscope that is placed in several spots in your home. If your floor is made out of concrete, it can be quite difficult to use this tool.

– If there is a leak in the drain, plumbers can use a camera. This is not very precise but can give an indication of what is going on. A water pressure test can provide a more accurate picture but this is harder to do. Some plumbers add a colored liquid to the water to detect where it goes. Smoke can be used as well.

You might have to open up the wall or floor to get a better look at the problem.

How to locate an underground leak

The first step is to find out if the water is inside or outside the house.

Underground leak outside the house

-If the leak is outside the house, it can be the responsibility of the water company if it is located before your system. If the leak is outside, discolored grass or plants can indicate a water leak.

To check if the pipes leak, In some instances, it is possible to isolate the sprinkler system and see if this leaks. Mapping out where the pipes run is a great idea as you might have to listen to hear the water flow using a specialized tool.

Tree roots often grow in drains outside. This can be detected with a camera or by adding a colored liquid in the water.

A slab leak can be serious and should be addressed as soon as possible.

Underground leaks inside the house

-If the leak is inside the house, we can try to find it by closing the valves of the system (for example hot water) and see if this affects the water pressure. This can provide a further idea of where the leak is located. This is quite similar to detecting a leak behind a wall.

A heat camera can be used to detect the leak. A lot of plumbers also use listening devices. It is often easier to find a leak behind a wall than under a floor as it is easier to hear through a wall.

To check the drain if wastewater is leaking, we can use a camera. A water pressure test can be used to see if drains leak as well.

Finding an underground leak can be challenging and the plumber might have to break open the floor in order to find it. It might be necessary to dig under the foundation if there is an issue here if you don’t want to open the floor.

What should you do if you hear water running being a will or find a leak?

If you find a leak, there are some things you should do to stop it. You should start by shutting off the water main water supply. Turning off the electricity is recommended as well if there is a big leak. Being fast is essential in this situation as water can get everywhere. Get a bucket and start mopping up the water. A wet vac can help as well.  There are companies specialized in drying your home. This is done with fans and dehumidifiers. This is very costly though as they have to come instantly. 

Wooden floors can get destroyed quite easily as they soak up the water. It might take some time before you see it but the wood can bend and break. It can take a while until you see the full extent of the water damage as it can affect your electric wiring as well. 

In a lot of instances, your water bill will be very high if you had a leak. Often it is possible to negotiate with your water supplier to get this down. They might try to highball you but if you keep insisting, they will probably lower the bill. Ask your plumber for assistance as they can create reports that allow you to get money back from several organizations. Plumbers are used to dealing with this situation and know what needs to happen.

Causes of water leaks

One of the most common ways for a water leak to happen is when fittings in your pipes leak. This is where two pieces of pipe come together. It is possible that the plumber didn’t make a good connection or that the material is getting old. If you get leaks in a fitting, it might be a great idea to check your whole installation. Steel (or galvanized) pipes might leak after a few decades so it can be a great idea to update your installation if you live in an older home. 

Another cause is that people turn off the heat during winter to save on their heating bills. This can freeze the pipes. Water expands if it is cold and the pipes will tear open. This can create a big leak. Therefore it is essential that you check your pipes during the winter and unfreeze them if needed. 

Sometimes people drill in a wall and they can hit a pipe without knowing it. This can leak for a long time as small drips might be unnoticeable for a while.

Faucets are often weak points as flexible piping is used. It can be a great idea to install a water sensor around them to get an early detection alert. There are also automatic water shutoff valves on the market that can detect when something is wrong and shut the water off. This can avoid a lot of damage as they limit the amount of water that can leak in your house.

There can also be an issue with the installation or materials. For example, copper can corrode if it comes in contact with certain materials. Asking your plumber to check your system is always a great idea. They can’t detect everything but can point out weak points such as pipes that are bent or don’t have enough support.

Too much water pressure can also lead to leaks. It is often possible to regulate the water pressure in your garage.

PEX systems often have a leak at the manifold as this is where the pipes are installed.  

Standing water is also quite bad for your system so use your faucets and toilets regularly.

Drains can leak if there is a clog or other issue. You shouldn’t flush wet wipes or pour cooking oil down your drains as this can clump together. These clumps can affect your drains. 

 In a lot of instances, there is a bad fitting that causes a leak. Sometimes the drains are not at the right angle or they are not well supported and this can cause issues as well.

 In the garden it is possible that tree roots grow in your drains and these have to be removed as they can break your pipes. Toilets are also a common cause of leaks. It is possible that the wax ring and toilet flange don’t fit well and this can leak some wastewater.


There are several ways to detect water leaks. This is not always to do and you might have to call a plumber that has special tools. Fixing a water leak can be done by adding a stop to the pipe and rerouting it or adding a new fitting. Shark bites are really easy to use and can help to replace a bad pipe if you have PEX-B pipes.