Turning leaks from headaches into opportunities
By Lance Anderson, Anderson Manufacturing Co., Inc.
A leaking pool is more than just a headache for the homeowner. The pool owner faces high water bills, excessive chemical usage, and the risk of additional structural damage. You, as their pool professional, are faced with the equivalent of finding a needle in a haystack. The average residential pool has over 1200 square feet of structural surface area and 100’s of feet of underground plumbing. In all of this area, you are looking for something as small as the head of a pin, (a 1/16” diameter hole can release 100’s of gallons of water a day). The task seems daunting. It’s no wonder many service technicians cringe at the thought of having to find a leak.
However, the reality is that this necessary part of any pool professional’s duties can become a truly profitable and satisfying part of your business (with a minimal investment in equipment, an understanding of basic physics, and a little bit of practice). Because leak detection is perceived to be a difficult task, those that have mastered the simple process find that they can charge premium service rates just to find the leak. Furthermore, most leak jobs directly result in additional repair, renovation, or liner replacement business.
How a leak professional finds a leak
Leak detecting is a mental game that involves synthesizing clues from a variety of different sources. The process of moving from initial identification of a leak symptom to exact location of the leak is most efficiently accomplished when the job is approached using a 3-step process.
Information you can gather that saves later steps
A pool owner’s concern generally results from the observance of some symptom caused by water escaping from, or something being pulled into (air or dirt) the pool system. The most obvious symptom of a leak is a dropping water level. However, increased chemical usage, excessive algae growth, high water bills, or evidence of water outside the pool may also be indications of a water loss problem that could be masked by an automatic fill device. Air or dirt being pulled into the pump and or blown into the pool is the most obvious indication of a suction side leak.
Before investing too much time in looking for a leak, it is important to assure that the symptoms you or your customer have identified are indeed the result of a leak and not some other problem. Check to be sure that air being pulled into the pump or blown into the pool is not the result of cavitations caused by an obstruction in the suction line or an oversized pump. Most importantly, though, check to be sure that water loss is indeed due to a leak and not evaporation.
Depending on a variety of pool and environmental conditions, evaporation rates can vary greatly and account for up to 1” of water per day.
To determine the evaporation rate of a particular pool, place a bucket filled with water into the pool on the first or second step, (this assures the water in the bucket is exposed to the same conditions as that in the pool). Fill the pool to its normal operating level and mark the water level in both the bucket and the pool. Measure the amount of water loss in both over a 24-hour period and compare the difference. If the bucket loses the same as the pool all of the water loss is due to evaporation and not a leak. This “Bucket Test” is something that the pool owner can be instructed to do without you having to make a trip to the pool.
Assuming the observed symptoms are indeed the result of a leak, gathering other information from the pool owner before visiting the pool can be helpful for later leak detection steps. Who built the pool? How old is it? What kind of pool is it? Are there any additional water features? Has there been any recent construction activity around the pool? When did it start leaking? The answers to all of these questions can be helpful in preparing for the job and confirming a suspected leak location.
A final step in this first information gathering phase is to make careful observations at the pool when you arrive. Look for obvious problems, especially around the equipment. Check the backwash valve to make sure water is not leaking to waste. If air is evident in the pump, try pouring water over the exposed fittings while the pump is operating. This often causes a leaking fitting to stop pulling air, temporarily eliminating the evidence of air in the pump. Careful observations at the pool site can provide many clues about a leaks location.
Putting the pressure on
Regardless of whether the leak is suspected to be in the plumbing or the structure of the pool, a pressure test should be done to provide confirmation of which parts of the pool are leaking, and which parts can be eliminated as suspected leak areas. This is important not only because it saves time in later leak location steps, but also because it allows the technician to provide the pool owner with the assurance that leaks that have been found and fixed are the only ones in the pool.
To do a pressure test closed test plugs are used to block off all but one of the exposed openings of a section of plumbing. A pressure induction system is put in the remaining opening (usually at the equipment). Water is then put into the line through the pressure tester and the system is brought up to no higher than 20 psi. A pressure drop indicates a leak. A line that holds pressure can be eliminated as a potential leak area.
While a pressure test of the entire plumbing system may be adequate in situations where a structural leak is suspected, individual sections of plumbing should be tested if a plumbing leak is suspected. Valves at the equipment can often be used to isolate these sections as long as they are tested first. Do so by testing from the equipment to the closed valves to see if they hold pressure.
Water is used for this isolation pressure test because it does not compress under pressure, and thus gives more accurate and quick results. Water is also advantageous for this test because if test pressures get higher than a safe level, plugs that pop out under water pressure will not fly from the openings as dangerously as those that pop-out under air pressure.
Accept no compromises when it comes to the sealing effectiveness of your test plugs. Tapered winterizing plugs have a tendency to pop out under test pressures wasting valuable time and putting anybody in the area at risk of injury. Plugs with straight-sided rubber and large corrosion resistant hardware allow for extra sealing area, easy expansion and ultimately more accurate results.
Your pressure induction system should allow for easy access to a variety of different plumbing openings and allow the introduction of either water or air (for later leak location steps) into the plumbing. A system utilizing various sizes of open stem plugs which can be quick connected to the pressure tester provides the ability to do this without having to cut lines or jury-rig fittings. A pressure tester must include a 0-30 psi gauge, hook ups for a garden hose and air line, a valve to control these and block off the system, as well as a means of releasing pressure from a line that has been tested but does not leak.
Follow your ears
Once the isolation step has been completed you should know whether the leak is in a plumbing section or in the structure of the pool. Different location methods will be used depending on where you are looking for the leak. To find leaks in underground plumbing, the most effective method is Sonic Location.
The key to effective sonic location is creating a distinct sound at the leak that can be detected with special listening devices designed to pick up vibrations in the ground. This distinct sound is created by getting air to escape from the pool leak into water saturated soil, producing a bubbling gurgling sound very similar to what you would here if you were to blow through a straw into a glass of water.
It is important to note that any water in the line will stay at the low end of the plumbing even as air is being added to the line. Thus, a good noise will not be produced until all of the water above the leak level has been purged from the line. To assure air is reaching the leak it is often helpful to purge all water from the line before attempting a sonic location.
Using the same pressure testing set up that was used for the isolation test, a constant stream of air from a regulated air source (small compressor or nitrogen tank) is fed into the line to maintain a pressure of no higher than 20 psi (5-10 is often enough). A listening device is then moved along the path of the buried line to detect the loudest most distinct sound. This sound will most often be directly above the leak. Listening devices are now available that also allow listening for leaks through the wall of the pool; a technique that often offers a more direct path to the leaking plumbing.
Dye Testing
Assuming there is no problem in the plumbing, the only place for the leak to be is in the structure (or shell) of the pool. Although sophisticated detection systems can be used for finding leaks in vinyl liners, finding leaks around fittings or lights in these pools, and in gunite pools still requires visual inspection.
Dye testing provides a means of identifying if visually identified leak locations are actually losing water. A small amount of dye is squirted within 5 or 6 mm of a suspected leak to see if that dye is pulled out of the pool with the escaping water. The pool should be filled to its normal operating level and the circulatory system turned off before dye testing. It is also helpful to assure that the pool has been cleaned prior to testing, as some leaks will be plugged up by dirt or debris and therefore will not draw dye.
A dye tester is simply a syringe that holds a concentrated dye and has several advantages over simple test reagent bottles that are commonly used for this procedure. First, it uses a long nozzle that allows precise application of the dye without creating unwanted water currents. Second, the syringe allows the dye to stay concentrated even when used while diving (squeeze bottles suck in water when released, diluting the dye).
The investigation of a concrete pool will start at the tile line and work down. The skimmer and any joints or cracks inside the skimmer itself as well as at the point where the skimmer bonds to the pool wall should be checked. Any penetration through the pool wall is a suspect location. Check around the returns, lights and finally along any visible cracks in the pool. To completely survey all parts of the pool, it will be necessary to get in the water. Diving equipment will allow your swimming pool leak detection professional a thorough survey of areas in the pool below what is reachable from the deck.
Skimmers, return fittings, stair gaskets and lights should be dye tested in a similar way in vinyl liner pools.
Tracking vinyl leaks with the LeakTrac 2200
Visually inspecting every inch of the liner itself is certainly a possibility. However, an electronic vinyl liner leak detector offers you a much faster and efficient solution especially in cold or dirty water.
Using innovative electronic technology, detectors such as the LeakTrac2200 will quickly find even the smallest leaks in the most complicated liner patterns while the operator stands on the pool deck.
The portable, battery- operated LeakTrac works by putting a small electrical charge into the pool water through a float that is positioned near the middle of the pool. A ground connection is made outside the pool at a ladder anchor, diving board anchor or a piece of conductive metal pounded into the ground, (screw driver or piece of rebar). The electricity put into the pool spreads out from the float in all directions seeking a way to complete its circuit and get to ground.
The electricity is drawn to any conductive penetration through the liner, creating a flow of electricity in the pool that can be detected with a probe attached to a telescoping pole. When the probe is pointed in the same direction that electricity is moving toward the leak a beeping noise is created. As the probe is moved closer to the leak, this beeping will increase in frequency until it becomes a steady scream when directly on top of it. Once leaks have been found and marked, repairs can often be made from the pool deck.
Conclusion
When leaks are approached following this systematic procedure, the entire leak detection process can usually be completed on most residential pools in a reasonable amount of time. While thoroughness and attention to detail are important, the process is not more complicated than most service professionals can handle. The tools and basic techniques that have been presented in this article, along with some hands on practice, are really all that are needed to turn leaks from headaches into opportunities to serve customers. Complete instructions and additional information are available on a CD-ROM program from Anderson Manufacturing Co., Inc. at www.leaktools.com