Getting started in leak detection begins with understanding that this specialty is equal parts skill, patience, and the right tools. Most professionals begin by mastering basic techniques — dye testing, bucket tests, and simple pressure checks — before investing in advanced electronic listening equipment and formal training.
So that’s where we’re going to begin, armed with useful advice from our allies at Anderson Manufacturing, leak detection specialists for more than 35 years.
Lance Anderson, owner of Anderson Manufacturing, says that a successful leak detection job actually starts when the customer first calls to talk about a leaking pool.
That first exchange of information — before the first trip to the pool — often eliminates wasted trips and assures that later detection steps are performed efficiently.
The primary objective is to answer the question: Is there really a leak?
Initial Information
In general, the person gathering this information is whoever answers the phone. It is important that this person has effective communication skills and tools for transferring the information to the person who will be doing the job. Consider devoting a specific area on your work orders for recording data from the informationgathering step. What information should be
gathered at this time?
Here’s what they should find out:
Type of pool? — Is it cementitious, fiberglass, or a vinyl liner pool? Is there an attached spa, waterfall, or in-floor cleaner lines? Each of these situations is going to be prone to different types of leaks and requires different types of detections.
Age of Pool? — Is this a brandnew vinyl pool where a poorly sealed seam should be suspected? Or is this an old pool that may need the liner replaced? Often pools that are built in certain time periods will have characteristic problems related to the prevailing building techniques and materials used at the time.
Who was the Builder? – Similarly, certain builders may use/ have used materials or building methods that are prone to a particular type of leak.
What is the normal level of pool activity? — Is this a pool that’s owned by a retired couple who keep it covered all the time except when they have people over for parties once or twice a month? Is this a pool that is constantly used by the family? Understanding the way the pool is used can provide valuable information related to the cause of the problem.
Has there been any recent construction or other notable events? — Has there been any construction activity or other suspect events recently? Cold winters often freeze pipes that have to be fixed in the spring. Earthquakes or heavy rains can also cause problems.
How long has the pool been leaking? — Finally, it is helpful to know how long the pool has been leaking. How do these suspect events coincide with the first notice of a problem?
The goal is to maximize the efficiency of the service technician’s time at the pool. A lot of very helpful information can be gathered during initial conversations with the pool owner.
Symptoms of a Leaking Pool
It’s a good idea for everyone on your team to understand the basics of leak detection, and that means knowing some of the symptoms of a leaking pool.
Unfortunately, many symptoms of leaks are also symptoms of other problems. An important part of the information-gathering step is to confirm that the observed symptom is actually the result of a leak.
Note: a good way to promote your leak detection service is to make your customers aware of the symptoms of leaks and make sure they call you when they first notice them.
• Air or dirt in pump or blown into pool.
• Difficulty maintaining pump prime.
The presence of air or dirt in the pump, or blown into the pool from the return lines is a good indication of a leak in the suction-side plumbing (from the pool to the pump). Eventual pump damage and cleaning problems may result if these symptoms are not addressed.
However, note that restrictions or obstructions in the plumbing, or an oversized pump for the plumbing, are non-leak-related problems that can also lead to the presence of air in the pump or blown into the pool. Such cavitations, however, are usually accompanied by a noticeable laboring of the pump.
• Structural Damage The more common symptoms of leaks are those that result from water being lost from the system. The first sign of a leak may be actual evidence of the water that has escaped from the pool. Wet, mushy, or unusually healthy spots in the lawn may be evidence of underground plumbing leaks. Structural damage, cracks, and settling of the deck or pool may also be indications of underground leaks. If left unrepaired, these problems can quickly become more serious.
• High water bills, excess chemical use, excess algae growth In pools with automatic fill devices, high water bills may be the first indication of a leak problem. Your customers may also notice an increase in the chemicals required to maintain proper balance, or that there is excess algae growth because the new water that’s being put into the pool is untreated.
• Dropping water level By far the most common indication of a leak is that the water level is dropping faster than what is “normal.”
The biggest challenge is to determine what is normal and thus avoid looking for a leak that is not a leak at all, but instead water loss due to evaporation.
Evaporation
There is no “normal” rate of water loss for a pool. Water loss due to evaporation is dependent on a number of different variables that will change from pool to pool, and even from day to day in the same pool. It is not acceptable to say that any water over ¼ inch a day is the result of a leak.
Evaporation rate depends on
• Air Temperature
• Water Temperature
• Humidity
• Air Movement
•Water Movement (fountains, waterfalls, etc.)
The water in a pool is made up of many molecules held together by low-level electromagnetic bonds. Energy (water temperature) causes these molecules to move. The more they move, the more of them will escape from their bonds with each other and evaporate into the air. This evaporation increases when the water temperature is higher in relation to the air.
As the water molecules escape, they form a layer of very humid air over the top of the water. This layer in effect creates a blanket that if not disturbed will eventually slow the level of evaporation.
Wind, which ends up being the biggest contributor to the evaporation rate, blows these molecules away, making room for more to evaporate. In addition to blowing away the high humidity blanket, wind will also blow molecules right off the surface of the pool. On a windy day, a pool can lose as much as ½ inch or more to evaporation.
For more information on how different weather conditions affect evaporation, and a tool that provides an estimate of evaporation rate based on your current weather conditions, go to www.leaktools.com/evaporationindex. html. Information here will be automatically calculated based upon current weather conditions in your area.
The Bucket Test
The bucket test provides a good estimate of how much water is being lost to evaporation.
The test involves exposing water in a bucket to the exact same environmental conditions as those affecting the pool and then comparing the amount of water lost in each. It’s a simple test that can be done by the pool owner or any pool tech.
• Fill pool to normal level.
• Turn off auto fill devices.
• Place a water-filled bucket on a step in the pool.
• Mark water level in each.
• Measure water loss in each after 24 hours of normal operation.
• Compare. Because the bucket only loses water to evaporation, while the pool loses water to both evaporation and any leaks, any pool water loss greater than the bucket is indicative of a leak.
How much water is the pool losing?
Loss in excess of evaporation (in inches) × 0.62 Gallons per inch per square foot × Pool Surface (in square feet) = Gallons of water lost The calculation shown above takes the water-loss information collected during the bucket test and translates it into gallons.
The reason that it is preferrable to describe leaks in gallons rather than inches of water lost is that the same water drop in different sized pools can be the result of very different sized leaks. A ½ inch water loss in a spa is the result of a much different leak than that which causes ½ inch loss in an Olympic-sized swimming pool. If leaks are measured, described, and compared in gallons, a much more accurate picture of the leak size is possible.
For example: A 20-foot by 40-foot pool lost ¾ inch of water in 24 hours while a bucket placed in the pool lost ¼ inch in the same period. How much water is being lost to the leak(s)?
(0.75-0.25) × 0.62 × (20 × 40) = 248 Gallons The increased accuracy that comes from describing leaks in gallons instead of inches is valuable for several reasons. First, this increased accuracy allows for meaningful comparisons of one leak to another. And, there is often more than one leak in a pool. If the first one found isn’t big enough to account for the gallons being lost, more searching will be required.
Second, describing leaks in this way is valuable for describing the level of urgency to the customer.
Gallons of water loss can easily be translated into the costs of the problem. Calculations of water replacement, resulting chemical costs, and the visualization of the structural damage and soil erosion resulting from the leak are often necessary to convince a customer that the problem is worth getting fixed.
For example, in San Clemente, California, water is billed in units of one hundred cubic feet (CCF), where 1 CCF = 748 gallons.
• Daily water loss: 248 Gallons
• Monthly water loss: 248 gallons/ day × 30 days = 7440 gallons/month Convert monthly gallons lost to CCF: 7440 gallons/month ÷ 748 gallons/CCF = 9.95 CCF Determine Applicable Water Rate: San Clemente's South Coast Water District uses a tiered billing system for residential customers: Tier 1: 1–10 CCF at 3.63/CCF Tier 2: 11–16 CCF at 4.61/CCF Tier 3: 17+ CCF at $4.73/CCF The 9.95 CCF lost per month falls within Tier 1 usage, assuming the leak does not push the total household consumption into a higher tier. If the household's total water use (normal use + leak) enters higher tiers, the cost would be higher.
We will use the Tier 1 rate for this calculation.
Monthly water cost of leak: 9.95 CCF × $3.63/CCF = $36.12
Pump on/Pump Off Test
The Pump On/Pump Off Test is a modification of the Bucket Test that gives an indication of what part of the pool is leaking.
If the Bucket test was done with the pool operating under normal conditions (pump running), a second Bucket Test with the pump turned off should now be performed.
Of course, the pool should be filled to its operating level again before this second test, and the water loss measurement for each test should represent the same period of time.
On > Off Suspect Pressure Side Plumbing On < Off Suspect Suction Side Plumbing On = Off Suspect Pool Structure
If the pool loses more water with the pump on than with the pump off, suspect a pressure-side plumbing leak (return or pressure-side cleaner line). These lines will lose more water when the plumbing is under pressure. If the pool loses more water with the pump off than with the pump on, then suspect the suction plumbing (skimmer or main drain lines). These lines are actually under a vacuum when the pump is running and they may not lose water unless the pump is off. A structural leak will lose the same amount of water whether the pump is on or off.
It is important to note that although these tests provide a good idea about where to locate the problem, any test that uses water-loss measurements over a period of as long as 24 hours only confirms suspicions at best. While this information is helpful, don’t invest too much time in getting it. If the customer can do it, that’s great. It is not recommended that you invest several trips to the pool collecting this type of information yourself. A pressure test will give the same information with a much higher level of certainty.
Water Loss Sensor
While both the Bucket Test and the Pump on/Pump Off Test require a period of 24 hours between water level measurements, a water loss sensor enables the same data to be collected in minutes. The LZ400, a water loss sensor, measures water level changes to 1/10,000 of an inch. This enables water loss of less than ¼ inch per day to be detected in seconds. The effect of pool water motion and waves are minimized through sophisticated mechanical and mathematical means, with the collected data displayed on an easyto-read LCD screen. A graphic displays water loss over time, while a detail screen calculates water loss rates in inches and gallons per day.
By graphing this miniscule water loss over time, it is possible to see a slope that represents the rate of loss in the pool. This slope can then be compared to a reference line representing a known rate of water loss. The LZ400 also provides an estimate of actual inches, or gallons of water loss per day, based on the pool size data entered at the beginning of the test.
Observations of the Pool
Careful observations at the pool can provide many clues that may not have been collectable through conversations with the pool owner.
These include:
• Visible leaks at the equipment. Look for water or water evidence around fittings.
• Leaky backwash valve. Check to be sure that water is not being lost to waste through a leaky or incorrectly positioned backwash valve.
• Air in pump or blown into pool. If air is evident in the pump, try pouring water over exposed fittings while the pump is operating. This often causes the leaking fitting to stop pulling air, temporarily eliminating the evidence of air in the pump.
Often air that is blown into the pool is partnered with sand or dirt that collects below the returns.
This is strong evidence of an underground suction side or plumbing leak.
• Signs of deck movement.
• Mushy spots in lawn.
• Signs of water damage.
• Other.
