Product Manual

4-1
Section IV
General Strategies for Water Leak Detection
Types of Water Leak Sounds
There are three different, commonly identified sounds produced by water leaks:
1. Pipe resonance and vibration from orifice pressure reduction.
2. Water impaction on the surrounding soil.
3. Water circulation and flow in the surrounding soil cavity.
Resonance or pipe vibration is often the loudest or most intense leak noise, sound-
ing like a "whoosh" or a "hiss." Water impaction and circulation are often weaker,
and often they may only be heard when the LD-12 user is very close to the leak
or directly over it. Water impacting directly on the soil is a "beating" or a rapid
"thumping" sound, and water flowing into the soil and around the pipe sounds like
a "babbling brook" or a mountain stream. If the leak has created a very large cavity
in the soil, these second and third sounds may not be heard at all.
Factors Affecting Leak Sounds
There are several factors that affect the loudness and the frequency range of
sounds made by water leaks in water pipes and transmitted to the surface of the
ground. These factors are:
1. Water pressure in the pipe (must be 25 psi or more)*
2. Pipe material and pipe diameter
3. Soil type and soil compaction
4. Depth of soil over the pipe
5. Surface cover: grass, loose soil, asphalt, concrete slab, etc.
* Pressuring to 50-60 psi or more will greatly aide detection. The intensity
or loudness of water leak sounds increases greatly with increasing water
pressure (see Figure 4-1).