Other than a giant, gaping hole ripped into the wall of your vinyl liner by the family dog, how can you tell when it is time to replace a pool liner? The first symptom is simply that the pool is not holding water. If water is escaping the pool then you need to either find and repair the hole, or replace the liner. If you suspect that you have been adding water to the pool more often than you remember adding in previous years then you might likely have developed a leak in the liner. To confirm, the first thing that you would do is a simple bucket test to see if the rate of water loss in the pool is greater than the rate of evaporation. So, other than the obvious, what are some other signs that a liner needs to be replaced?
Liner Slips Out Of Coping Track
One of the most telltale signs that a liner is reaching the end of its service life is that it keeps slipping out of the coping track that holds it in place. A "liner pull" as it is called, is not always a sign that there is a problem with the coping. It could be that the coping is fine, but the vinyl has lost (or is losing) the stretch than newer vinyl has. Every year that the liner gets older, the more pull and stress it puts on the coping track. Eventually the liner loses near to all of its elasticity and this results in the liner pulling out of the coping track. If the liner is so tight that it is pulling out of the coping track then you should replace the liner before it starts to damage the coping. Eventually there will be so much stress on the coping track that it will crack (PVC) or stretch (aluminum). If left like this too long then you will find that you need to replace the coping as well as the liner. On pools with a deck integrated coping this can prove to be very expensive, costing far more than just the liner replacement itself.
Fading Liner Colors
While fading colors of your liner do not constitute a reason to replace your liner itself, fading is an indication that the liner is getting old and will need to be replaced sooner rather than later. UV inhibitors are added to the vinyl during the vinyl manufacturing process. These UV inhibitors are expensive and cheap vinyl versus expensive vinyl often comes down to how much UV protection the liner has. If your liner is fading, especially above the waterline, this is an indication that the liner is failing. Eventually the liner will tear in these areas and often this will happen suddenly when adding water to the pool or trying to stretch the liner back into the coping track if it has slipped out. If you notice aggressive fading in the color of your vinyl liner then you will need to replace it soon. If your liner is only a few years old and you notice this fading then you might have purchased inferior vinyl with not enough UV protection added to it. Vinyl that fades quickly could also be due to poor water chemistry however this would affect all of the liner, not just the parts above the waterline.
Problems Around Return & Skimmer Flanges
There are a number of different kinds of problems that can develop around the return and skimmer flanges in a vinyl liner pool. These can include wrinkles in the liner under the flange, bumps under the liner, or rust stains visibly developing around these areas. Some of these problems are from failures in the liner, while others are an indication of a failure of the flange and gasket itself. Regardless, if you are seeing problems around the flanges of your vinyl pool then this might mean the liner will need to be replaced. The older the liner is the more likely that any serious problem around the return or skimmer cannot be dealt with without also replacing the liner. Conversely, the newer your liner is the more likely that there is enough stretch left in the liner to perform more serious repairs. Ultimately if you have water escaping the pool at the returns or skimmers then you need to stop it one way or another and many of these repairs require replacing the liner.
Something that experienced pool technicians understand is that a pool can leak water but continue to be operated and used day to day. Even serious leaks can sometimes be hidden from the pool owner as the pool will slow down the rate of water loss once the entire area around the pool is also saturated with water. These somewhat misleading symptoms of water loss often lead to pool owners operating their pools for extended periods of time with water leaking from the pool. It is this chlorinated water from the pool that leads to additional problems and the potential for expensive repairs. If you receive advice from a pool technician that it is time to replace your liner, then you should strongly consider this option as opposed to getting "one more season" out of your leaking liner.