Leak Detection and Science and the Art

Domestic Systems Hot & Cold:

Leak Detection is as much an art as it is science and equipment. Having the proper equipment starts with a qualified leak detector (plumber) that has experience. The best hardware and equipment is nothing without a good leak locator technician. Make sure the company you hire has both.

What is a slab leak? A slab leak can be domestic water that you drink leaking under the concrete slab of your home. This is the pressurized water coming into your home. This leak is a constant and can usually be heard and detected by a noise of running water in some cases. One other symptom you have a domestic leak are higher than normal water bills. The other type of slab leak is the sanitary sewer or drain lines leaking under your concrete slab. This might be something you do not notice because everything is working fine.

I know I have a domestic leak how do you locate it? The first thing to do is to isolate the hot and cold water systems. This is done by turning off the ball valve or gate valve at the hot water heater. This valve might need to be changed if it is in poor condition or not working properly. If the leak stops at this point we know we have a leak in the hot side of the domestic system. If the leak continues we have a leak on the cold side of the system. Lets assume the leak is on the cold side. The next step would be to listen to the service valves at the appliances and fixture. This will give us a sonic or sound register. This sound register will tell us which end of the house to look for the leak in. The next step would be to energize the water lines under the slab in the effected area. We would locate the water lines and mark the slab for reference points. This will tell us how your water service runs under the slab. The next step is take sound reading with your leak locating equipment over the areas that you have located the lines. This first reading is with the water on. Next we turn off the water at the street and turn off the valve at the water heater and energize the system with air. The reason we do this is to localize the leak. We energize the system with air from 1 psi to over 20 psi. Warning if the system is PVC this could be dangerous. PVC is not rated for air and will void your warranty. Once the system is energized with air we take another set of readings and make a final determination as to the location of the leak. At this point we are able to give the customer an estimate for repairs.

What symptoms I have a sanitary sewer slab leak? In north Texas you might have foundation problems caused by a sewer slab leak under your slab. Other issues you might experience are mold issues, odors coming from drains, wet areas around your home and pest problems ( termites, ants, roaches and other home intruders.) Again the sewer system might be working fine but these issues can surface before the sewer has a problem.

Sanitary Sewer Slab Leaks

Leak Detection and finding your sewer leak under slab.  The first thing to finding a sewer leak is knowing that you have one. The way to test a sewer leak is through a static test. This is the same test done when your home was built. It’s really very simple. The first thing to do is locate your cleanouts for your sewer service leaving the structure. This will be in the ground usually in front of or behind your home. Once the cleanouts are located we insert a test plug or ball in the sanitary sewer and inflate the ball to seal it off. Once the sewer is sealed we fill the system up to slab level and monitor the water level for 20 minutes and note if there is any loss or change in the water level. If there is a loss you have a leak in the system. This does not tell us were the leak is. This test tells us we have a leak only. The next step is to locate the leak or problem. This is done with a video inspection unit ( sewer camera. ) The camera  is used to inspect the sewer system and locate your problem areas. Usually a break in the sanitary system can be seen and located quickly. Once the problem area has been found the technician can turn on the transmitter behind the camera head and find the transmitter with a handheld locator. This will give him the area and the depth of the pipe and orientation. If the area can not be easily seen with the camera the technician will have to do isolation testing to find the leaking area.

Sewer Isolation Testing and Leak Detection   Isolation testing is do in tandem with the camera. The isolation testing is done with a test ball where certain parts of the sewer system a sealed off and tested separately. Once we know which part of your sewer system has a leak, we can test it in sections until we come the area that is leaking. It is not as easy as it sounds but this is the basic concept.


Leave a Reply