THE ANATOMY OF WATER LEAKAGE


by
Charles C. Roberts, Jr.


Water leaks from plumbing in inaccessible areas can be difficult to find. When the water leakage is sighted, it is tempting to conclude that the point where the water is seen is the location of the leak. This may or may not be true. Many times, water will travel laterally above sheet rock and leak at a joint far from the source.

Figure 1


Figure 2


Figure 3

Figure 1 is a view of such a condition. The arrow on the right is the location where water was found leaking from plumbing pipes in the ceiling. The arrow on the left points to the actual leak in a water pipe. Figure 2 is an infrared thermogram of the ceiling in the vicinity of the leak. In the thermogram, lighter shades indicate higher temperatures than shades of gray, which are colder temperatures. The warm, bright thermal pattern from the ceiling light is a reference with respect to Figure 1. The dark thermal pattern on the ceiling is water in the ceiling sheet rock from the leak and appears dark, or cold, due to evaporative cooling of the water. It should be noted how the water pattern has spread out laterally over the sheet rock and only appeared to be leaking at a joint between pieces of sheet rock. The arrow points to the location where water was observed leaking from the ceiling. Figure 3 is a thermogram showing the scene with the hot water turned on. The light spot on the thermogram is hot water leaking from a pipe in the ceiling.

Figure 4

Excavation at that site showed the leaking pipe in Figure 4. Apparently a screw driven through a wood joist to support another pipe contacted the outer diameter of the copper water pipe, forming a partial penetration. Thermal cycling of the pipe over the months caused failure of the pipe wall and eventual water leakage. As with many water leaks, finding the source may be difficult. Lateral movement of water may not be predictable, leaving little clue as to the source. The leak can be intermittent as it was in this case. The water only leaked when hot water traveled through the pipe causing thermal movement and leakage. When the water cooled from lack of use, the pipe would move into a position where the screw sealed the leak. In this case, infrared thermography was able to locate the source of the leak, minimizing the time and ceiling damage that could have resulted from more traditional means of locating the leak source.


Figure 5


Figure 6

Figure 5 is a view of joists and flooring near a leak in a copper water pipe. The warped and deteriorated floor sheathing is evident in the photograph. Figure 6 shows the water pipe with a corrosion related pinhole that caused the water damage. The pinhole on top of the pipe sprayed a fine stream of water directly at the wood sheathing, showing little evidence of water leakage in the crawlspace. The water moved horizontally throughout the sheathing, badly damaging the floor, another example of water damage far from the source. The anatomy of a water leak is often complex since the source may not be visible. Horizontal movement of water tends to obscure the source. Instruments such as infrared cameras and ultrasonic testers can help, but are not always successful in finding a leak.


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