What Are the Causes of a Pinhole Leak on the Side of an Above-Ground Pool?

Old Liners

• Vinyl swimming pool liners are sold in a variety of thicknesses, ranging from 20-gauge vinyl to a heavier 30-gauge vinyl. The more economical liner is the 20-gauge, but regardless of the size you purchase, all liners will eventually have to be replaced. As a liner ages, it becomes more brittle and subject to deterioration. This leads to tiny pinholes in the wall and floor of the liner that will create a series of invisible leaks, resulting in slow but consistent water loss.

Other Causes

• Pinholes are tiny holes that are rarely caused by something other than liner deterioration. Liners are know to rip from contact with sharp objects and punctures on the pool floor. A pinhole leak in the side of the pool is hard to detect. The benefit of having a tear in your pool is that it's easily recognizable, and you know you have a leak. With pinhole leaks, you are slowly damaging the interior of the pool walls without you even knowing it. Eventually, the pinholes will tear open further, causing more persistent water leaks.

Evaporation

• Don't always assume that your pool has some kind of invisible pinhole leak and that something may be wrong with your liner. Evaporation can contribute to your pool losing several inches of water per week. Weather conditions such as high winds, increased temperatures and low humidity also play a role in water loss. Apply a solar cover to the surface of your pool to eliminate evaporation. If your pool is still losing water without anyone actually using the pool, then there may be a leak.

Leak Detection

• A good way to tell if your pool is losing water from a pinhole is to perform what is referred to as the bucket test. Place a 5-gallon bucket of water beside the swimming pool. Mark the water line with a permanent marker on both the bucket and pool. Wait a full day, and then go back outside and monitor the results. Measure how much water was lost in the pool and in the bucket. If you lost more water in the pool than in the bucket, you have a leak.