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It's a Jungle out there. Underground Utility Detection & Inspection Services

Leak Detection


Leak Detection in Oregon (Eugene & Portland) and Washington State (Everett, Renton, Seattle, & Tacoma)

CNI Locates provides acoustic underground water leak detection services. We also provide thermal imaging leak detection and tracer gas leak detection services. Thermal imaging leak detection is commonly used for the interior of buildings and can be used in conjunction with other water leak detection services where needed or applicable. Tracer gas leak detection can be used in interior and exterior work areas and is commonly used in conjunction with other underground leak detection services like acoustic leak detection and thermal imaging.

Understanding Acoustic Leak Detection

Underground water leaks in pressurized pipes may make many different sounds: 

The “Hiss” or “Whoosh” sound, which often sounds like constant static noise, is the only sound which is always present for water leak detection in pipes with 30 psi or higher water pressure. The other sounds may or may not be present, and usually, they are not as loud. So, we decide, “Is there a leak?” by listening for a “Hiss” or “Whoosh.”

What Factors Affect These Sounds?

Several factors affect the loudness and the frequency range of the sounds made by water leaks transmitted on the pipes and transmitted to the surface of the ground:

The loudness or intensity of the leak sound is directly proportional to the water pressure inside the pipe (up to a limit):

Metal pipes, such as iron mains, copper services, and steel pipes, transmit water leak sounds that are a louder and higher frequency than PVC pipes or asbestos-cement pipes. Thus, knowledge of the pipe material is important.

Large-diameter (concrete, PVC, iron, steel, etc.) pipes transmit less sound from water leaks than small-diameter pipes. Large-diameter pipes also transmit lower frequency sounds than small-diameter pipes.

Sandy soil and very loose soils, particularly over a freshly buried pipeline, do not transmit the sounds of water leaks very well, nor do water-saturated soils such as bogs and swamps. Hard, compacted soil transmits the sounds of water leaks best. Soil absorbs the sounds of water leaks very quickly. Leaks in water lines that are only 3 or 4 feet deep are much easier to hear at the ground’s surface than leaks in deeper lines. At 7 or 8 feet deep, only very large leaks with good water pressure will produce enough noise to be heard at the surface.

Finally, the ground cover, whether an asphalt street, loose dirt, concrete slab, or grass lawn, also makes an important difference. Hard street surfaces and concrete slabs resonate with the sounds of the water leak, which may be heard for 5 to 10 feet or more on either side of the water pipe. Grass lawns and loose dirt surfaces do not offer such a resonating plate-like surface, and their surface variations make firm contact more difficult.


How Do Leak Sounds Travel on Pipes?

Metal pipes, particularly iron mains between 6 inches and 12 inches, copper services, and steel pipes transmit the sounds of water leaks for hundreds of feet in every direction. Asbestos-cement pipe and PVC pipe do not transmit the sounds nearly as far. Distances transmitted for the “Hiss” or “Whoosh” sounds of water leaks are a function of the pipe diameter as well as the pipe material:
Thus, knowledge of the pipe material and diameter is important to know how far the leak sound may be transmitted along the pipe walls.

How Do Leak Sounds Travel Through Soil?

Soil absorbs water leak detection sounds very quickly:

Soil absorbs the high frequencies to a greater degree than the low frequencies. For a leak in a pipe 6 ft deep, the “Hiss” or the “Whoosh” sound is weak and “muted,” i.e., only the lower frequencies are heard. The sound is louder and slightly higher in frequency for a leak in a pipe 3 ft deep.



“Surveying” is the term for listening to water leaks when there is no obvious evidence, like water flowing on the street. Every hydrant, valve, and service line are a possible location to hear the sounds of water leaks. Since the sounds travel on the pipe walls better than through the soil, always listen to the hydrants, valves, and meters first. As you get closer to the leak, the sound gets louder. Finally, decide which two of these locations are the loudest. Now you are ready for “Water Leak Pinpointing.”

Surveying at a Hydrant and a Service Line:


“Water Leak Pinpointing” is a common term that is applied for the process of pinpointing an exact leak location. For Acoustic Leak Detection the exact leak location is usually the spot where the leak sounds are the loudest. To find this spot, the leak detection expert must carefully mark the location of the water line in the work area with a pipe and cable locator. Usually, on water mains, the piping between the valve or hydrant with the loudest sound and the valve or hydrant with the second loudest sound is the section of the line that needs to be marked. The section must be accurately located and marked in the area for the leak detection expert to listen directly over the pipe consistently. 

Expert technicians at an underground water leak detection company move the ground microphone 2 to 4 feet each time in the direction of the water line, listening and moving closer to the water leak. When a leak detection specialist is moving the microphone, they do not adjust the volume control since the volume control must be held constant to make accurate comparisons. When a leak detection specialist is very close to the leak, it may be impossible to decide, based on the user’s hearing alone, whether the leak is in one spot or 3 to 4 feet away. When this occurs, the leak detection expert must study the visible display (meter) to see if the signal is slightly stronger at one location than at another.


Leak Facts


You may have a plumbing leak if:

Contact a professional plumbing leak detection service like CNI Locates when you are having troubles finding a plumbing leak.

You may have a pool/spa leak if:

Contact a professional pool leak detection service like CNI Locates when you are having troubles detecting pool leaks.

Pool & Spa Tips


The “Bucket Test” will determine if water loss in a pool is due to evaporation or a leak:

Contact a pool leak detection professional at CNI Locates for help detecting pool leaks & spa leaks.


The “Meter Test”:

Conservation Checklist

Saving water is like any other habit. The more you do it, the more natural it becomes. It’s fun to find more ways to conserve, becoming water-wise.

Speaking of saving, be sure to save this water leak inspection checklist. Hang it in a handy place – like your utility room. Use it to do a full leak detection check on your house four times a year. Just seeing it will remind you that conservation pays and preserves precious water. 

Sometimes a small investment can pay large dividends. For example, buying a low-flush toilet can save over 18,000 gallons of water a year! It’s up to all of us – individuals, businesses, and industries – to save the earth’s resources. So, remember wherever you go, take your water consciousness along. What works at home, works at the office!

In General

In The Kitchen/Laundry


In The Bathroom



Other Conservation Tips

Make your move today towards a wiser use of our resources. When it comes to conservation, every effort helps. Check out what you can do, then make it a habit!
Save a resource. It’s money in the bank!

Thermal Imaging Leak Detection

Thermal imaging is generally used to locate water leaks in building interiors. Still, it can also complement exterior leak detection methods and help quickly identify leaks or where moisture is gathering. If you need professional leak detection help to find interior leaks, or leaks along windows, roofs, floors, and around the usual water pipes inside your structure, call us today. We can pinpoint leaks and sources before you do any demolition work, saving you time and money. 

We can use thermal imaging in conjunction with other water leak locating service applications. When we detect leaks, we think moisture or heat signatures can be useful to help provide a complete picture of your situation. 

We use the FLIR MR176 and C3 with the MR40 Moisture Pen for infrared camera thermography for water leak detection.

Contact CNI Locates for An Array of Professional Leak Detection Services
Contact Washington and Oregon’s number one water leak detection company today at (877) 826-1177 or email [email protected] to go over any questions or concerns you may have. All we need is 24 hours’ notice Monday through Friday to schedule a leak detection service for the next business day.