1. The sounds of leaks in pressurized water pipes can travel for hundreds (even thousands) of feet in every direction down the mains and services:
2. Different pipe materials and different pipe diameters transmit leak sounds down their pipes very differently:
| Pipe material & diameter | Typical distance sound travels |
|---|---|
| Cast iron – 6 in | 1,000 – 1,200 ft |
| Cast iron – 12 in | 800–1,000 ft |
| Cast iron – 24 in | 600–800 ft |
| AC – 6 in | 800–1,000 ft |
| AC – 12 in | 700–900 ft |
| AC – 24 in | 400–600 ft |
| PVC – 6 in | 400–600 ft |
| PVC – 12 in | 200–300 ft |
| PVC – 24 in | 100–150 ft |
3. The service line material is also very important when listening at meters or curb stops:
| Service Line Material | Typical distance sound travels |
|---|---|
| Copper Tubing | 600 – 1,000 ft |
| Galvanized Steel Pipe | 800–1,200 ft |
| “Poly” Plastic Tubing | 50–100 ft |
4. The leak survey “strategy” must consider the pipe materials, pipe diameters, service line materials, and types of leaks expected.
If the distribution system experiences main breaks (5 to 10 gal/min or more) at certain times of the year and the mains are iron pipe or A/C pipe, then a “Hydrant Survey” can be effective and an efficient use of time. Listen at every hydrant in every block. If there is no hydrant for 500 ft., then choose a main valve.
If the distribution system has PVC mains and copper services, then an “Every Meter and Every Valve Survey” may be necessary. Particularly if the system experiences small leaks at the corp valves (taps into mains).
5. If you hear a leak, listen at the adjacent service lines, hydrants, and valves. If the sound is louder, then you are closer. If you cannot tell which one is louder with your ears, then study the two-digit display:
