Non-invasive leak detection techniques: How service techs can identify leaks in vinyl-lined pools and rule out false positives

Probing the liner

A complete vinyl liner leak detection kit should include a float, a proper ground rod, and voltage transmitter. It should also include probes designed for identifying where a ground appears on both horizontal and vertical planes. The design of these probes will help divert the user from picking up on false positives. When a floor probe is in the pool, the angle of the probe directs the sensitivity toward the floor and reduces the effect of grounds showing from lights and ladders giving the impression of a leak. The same effect occurs when a wall probe is facing a vertical surface. Potential ground sounds from screws in drains are less evident depending on the direction the probe is pointing in.

After the technician has listened with a hydrophone, it is time to begin scanning the vinyl liner with the applied voltage of the leak locator. The user will insert the ground rod into the soil near the pool. If the soil is extremely dry, simply using a hose to wet the area before inserting the rod can ensure better results. Note: Inserting the rod below the surface offers the best results when connected to the transmitter device.

Float

When a device uses square voltage, the float can be placed anywhere in the pool and will distribute the voltage equally throughout the vessel. It is important to remember the float can serve as a ground source and show a false positive reading. Therefore, the author advises placing the float near an area that has been previously cleared of a leak, such as a pool light, ladder, or skimmer. The square voltage applied from the transmitter is evenly distributed into the pool via the float and is attached to the ground rod, completing its circuit by finding a ground beneath the pool liner. When the voltage reaches a ground, it is discoverable using the probes, which emit a pulsing sound through the receiver that alerts the user to the specific area of the leak. A headphone amplifier allows the user to hear the pulsing sound created by the device when it identifies a leak. As the probe gets closer to the leak, the pulse quickens and increases in volume. The noise can begin as far as a few feet away from the leak. When passing the leak and moving away from it, the sound slows and becomes quieter. This allows a technician to precisely locate the area where water is escaping the liner into the ground. Since the water does not necessarily flow as it would through a pipe or a crack in concrete, using an electric voltage to find where the water meets a ground behind the vinyl liner is the best option to discover the leak. Where water might need to pull with a stronger flow for dye to show being ingested into the area of a leak, an electric voltage will easily show smaller leaking areas where water meets a ground and the leak is found. Should the technician then decide to dive a pool and use dye to test the specific area, this can be performed as a back-up measure to show and mark the location where repairs need to be made; however, this is not mandatory.

Setting up the connection

While this technique has been described using a ground rod in the soil next to a pool, a vinyl liner may be laid over a concrete shell, or the pool may be located inside a building where dirt is not accessible. There are alternatives for setting up the ground wire in the case of a large indoor concrete patio or when the walls separate the inside pool area from the outside. In this case, for setting up the connection without using the actual ground rod, the connecting wire can be applied to anything grounded in the pool area, such as a light pole or metal conduit, which goes into the ground from inside the pool environment. Conduit can often be painted over—sometimes with several layers of paint. The thickness of the coating can hinder the transmitter’s ability to find a ground. It is recommended to attach to a clean metal area with ground wire or to remove a small section of the paint to get a clean connection between the wire connector and the metal. This can greatly enhance the performance of the unit.