Rarely does a leak pose a serious threat to a pool - it does not command the attention of a broken pump or even a clogged filter-but it can be an annoying and persistent burglar of water and chemicals, and if allowed to linger it may invite other, more serious offenders such as algae and structural damage to the homeowner's backyard.
There's the sense of loss, of something not right with the pool, that owners find a source of unease. In any case, leaks both large and small can be unmasked and corrected with a bit of detective work and relatively inexpensive leak-repair products. It's a satisfying fix, and it makes the service tech look like a hero.
The Scene of the Crime
Like any good detective, start by viewing the scene as a whole, then begin to focus on the details. Sometimes the culprit has left an obvious calling card. Is the ground settling around the pool, are tree roots pressing into the plumbing, rusty fittings falling to bits? These are just a few of the often-conspicuous clues which lie in plain sight.
But wait - just like a service tech responding to a call for "leak repair," we may be getting ahead of ourselves. Are we certain there's a leak at all? Sure, one or more of the symptoms may be there (dropping water level, leaping chemical bills, algae growth) but these are not necessarily the result of a leak. Any one of them might be the result of other causes.
For instance, notes Lance Anderson, owner of Anderson Manufacturing Company, a pool products manufacturer that specializes in leak detection and repair, air bubbles in the plumbing may be caused by pump cavitation. And even if a significant drop in water level has been noticed, it may not be from a leak. "Depending on environmental conditions," he says, "evaporation rate can vary greatly from one pool to another or even from one day to another."
A simple test can tell if water is being lost from the vessel through normal evaporation or from an actual rupture somewhere in the pool wall or piping. Take a five-gallon bucket, fill it with pool water and set it in the pool on the first or second step. This assures that the ambient and water temperature conditions for our tiny test pool (the bucket) are the same as the large one we're investigating.
Now mark the water level for the water in the bucket and the pool. After 24 hours, the drop in water level in both the bucket and the pool will be the same if there's no leak. If the big pool has lost more than the little test pool, water is escaping through a hole somewhere.
Note that you don't necessarily have to do this straightforward test yourself. It may be to your advantage to have the homeowner perform this uncomplicated procedure in advance.
Having decided there is definitely a leak, the next step is to locate it. A few questions can help get you started. Anderson suggests a short interview with the owner to determine who built the pool and when. What kind of pool is it? Are there any additional water features? Has there been any recent construction activity around the pool? When did you first notice the leak?
A careful examination of the pool is in order. Focus on the equipment first, says Anderson: "If you've detected air in the pump, try pouring water over the exposed fittings while the pump is operating. This often causes a leaky fitting to stop pulling in air, temporarily eliminating the evidence of air in the pump." While you're at it, check the backwash valve to be sure that it's not leaking or that no one has left it on the wrong setting.
It's time for a pressure test to help pin this leak down. The system must be sealed with plugs (part of your leak detection and repair kit, purchased from a reputable supplier) and pressurized with water.
"A good set of test plugs with effective seals is essential for this," according to Anderson. He prefers straightsided rubber plugs to tapered winterizing plugs, which can pop out during a test.
Close off all openings to the system, and then charge it with your pressure tester (no higher than 20 psi). Check your gauge. If the pressure drops, there's a leak.
Pressure tests of individual sections will be needed to get a better fix on the rupture. You can use the equipment valves for this as long as you test them first to make sure they're good and tight.
Follow Your Ears
At this point, the leak has been located either in a specific place or section of plumbing, or it is in the pool structure. If it's in the plumbing, use your ears to get the precise location, same as you would to find a hole in a bicycle tire. With the system outlets still plugged, force a steady stream of air into the suspicious section. "In order to get the air to flow through the leak," Anderson says, "the water above the leak must be purged from the line. Once that is achieved, and air is moving continuously through the pipe, you will notice a bubbling sound as it escapes into water-saturated soil."
As you move along the ground above the buried line toward the leak with a listening device from your leak detection kit, the bubbling sound grows louder. When it reaches peak volume, you are directly above it. Go get your spade.
If the leak is in the pool shell - that is to say, you have a leak, and it's not in the plumbing or equipment - you may be able to find it by looking carefully at the usual suspects and confirming your suspicions with a dye test.
The "usual suspects" are old tile and any place where the pool wall is breached, such as a light fixture, a skimmer, a return or, of course, that enormous and clearly visible crack in the pool shell surface. A squirt of dye close to the wall will disappear through your leak like a rat down a sewer hole, and voila, you have found it.
With the leak precisely located, the hard part of the job is finished. A straightforward pipe or equipment replacement in the plumbing is all that remains, or in the case of a poolshell leak, a good quality pool patch or sealer will do the trick.
High and Low
If these relatively low-tech leak detection methods do not yield the desired results, there are products on the market that can help locate it with sensitive listening gear or electrical discharge. The electric discharge machines use the natural, excellent conductivity of water and the electrical insulating properties of an intact pool wall to find the leak. When a small electrical charge is released in the pool, it cannot penetrate the pool wall but will follow the leaking water in its quest for ground. A floating indicator points to the leak.
With these methods and a bit of experience, finding pool leaks can be not just profitable but enjoyable for those who enjoy a good puzzle. And as Anderson points out, the pool tech who discovers and fixes a leak never fails to impress the client - which can ultimately lead to a premium charge.