Warning Signs for a Slab Leak

Are you concerned about a slab leakage? Perhaps you have heard a low-pitched sound coming from your faucets after they are turned off.

Perhaps there’s a warm area under your floor that you have noticed over the past few weeks. No matter what the reason, this article will show you how too quickly and easily test for hot water slab leak. 

slab leak is generally an issue with one of the copper pressurized water pipes running underneath the concrete slab foundation. A poured concrete slab foundation is a common feature in Long Beach, CA. 

Leaks from concrete slab foundations are more expensive and difficult to fix than other foundation types. A pier and beam foundation could be used for older homes in Long Beach, CA. This test is more straightforward and can be used to repair the problem.

Your home may have plastic water lines, called PEX, installed through your attic if it was built after 2010. This will protect your home against a slab leakage and allow you to access plumbing more easily.


To perform this test, you will only need a functioning shutoff valve for your water heater. There is a high chance that the water heater’s old gate valve (round-shaped handle) has not been used in years. This test is easier if the water heater has an easy-to-use ball valve (lever-style hand).

First, make sure no faucets are leaking. Make sure that all faucets, including those for the tub/shower, are working properly. You don’t need to worry about outdoor faucets or toilets. They only have cold water. Prior to testing it out, make sure to fix any leaking faucets or running water. Make sure everyone in the house knows that you are testing the system. You should tell them to stop turning on faucets until you’re done.


After you have checked everything and found no leaks, turn on your water heater. Make sure the recirculation pump is unplugged if it exists. Next, turn off the cold water supply valve. It will be located at the top right side of the water heater when it is facing you. It should be at the top right of your water heater.

After waiting for approximately 2 minutes, turn the valve off and on again. If water is rushing through the valve when you turn it on, you may have a slab leak. If you don’t hear any sound, it is likely that there isn’t a slab leak. If the test is not conclusive, you can do it again and wait for a longer time.

A hot spot or warm spot on a hot water slab is another sign of a leak. Make sure to check all areas around your house for these signs. To narrow the problem, you can either use your hands (or an infrared thermometer).


You can create a closed-system by closing the valve and making sure that all hot water fixtures aren’t leaking. If there are no leaks the pressure will remain the same so there won’t be any flow when you turn it on.

The pressure will drop over the 2-minute interval if there is a leak. When you turn off the valve, water will flow through it to replace the water lost. It’s like heavy traffic at the stoplight. Ever been stuck in traffic so bad you couldn’t drive anymore when the light turned green? The traffic light is your shut-off valve. It is located on the right side of the road. This is where you will find the hot water pipe system.

Traffic movement is not affected by whether the light is green or red, as long as there is traffic backing up from the accident. Traffic movement will occur if one lane is opened and the traffic behind it is “leaked”. Conventional hot water pipes are not buried in the backyard. If one of the pipes leaks, it will be either below the slab or within the house. You would have seen water damage if it were inside your house.

This reasoning can be used to determine that the slab’s hot water pipe is leaking. This evidence can be combined with other evidence such as a warm floor or high water bills, hissing sounds, and it becomes very conclusive.


This test by itself is not foolproof. It is possible to connect the hot and cold systems in another location (e.g. a shower valve). This situation is not uncommon. If it does, shutting off the cold water valve at the heater will not isolate the hot system. The test won’t be successful.

Although this type of test can be performed without the use of a tool, it is more difficult for cold water systems. This is because you have water lines running through your yard and other water lines that serve the irrigation system. Nonetheless, this test can be performed at the water meters or by simply watching the flow indicator. It won’t determine if there is a slab leak.

You can test the cold system if you have a good ball-valve where the main water line enters your house. However, be careful of false-positives like slow-running toilets etc.