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Case Study: Long Plumbing Run with Multiple Leak Noises


Type of Pool:

Concrete – Commercial Pool


The pool cleaner noticed that suction was not as strong as it used to be, which caused difficulty when cleaning the pool. There wasn’t significant water loss, so the customer didn’t suspect a large leak.



We started by shutting the pump off and running a static dye test using Dye Testing Cones. The line that included all five skimmers did not pass the static dye test, which indicated that there was a leak somewhere in that line. We then moved on to running a water pressure test on the line. The pool equipment was about 250 feet away from the pool, so it took a long time to build up pressure. Once pressure was built up, it  dropped quickly, confirming that there was a leak in the pipe.

To locate the leak, we needed to get pressurized air to escape through the leak into water saturated soil. This makes the telltale bubbling sound that can be picked up by our Fisher listening device. To ensure that air reached the leak, we attempted to purge all the water from the line by inducing air. But, because the plumbing run was so long, it was hard to be certain that all the water had been purged. When we tried inducing air into the line from one of the skimmers we heard the leak noise in several areas along the plumbing run.  Noise in several spots can indicate that there are multiple leaks, but could also be caused by low spots in the plumbing where the induced air is traveling through standing water still in the pipe.  This is most likely to happen when inducing air from the low end of the plumbing.

Changing where the air pressure is being induced from can help rule out low spots and pinpoint the leak location. In this case, since we heard multiple leak noises, we changed to inducing pressure through a different skimmer on the other side of the pool. When air was induced from this skimmer, we heard a leak noise on this side of the pool but there was no longer a noise on the other side. The only place that made a leak noise from both induction points was between the two skimmers. So, that place was the most likely leak location. To verify that there wasn’t a leak farther down the line toward the equipment, we switched the induction point to a final location in the pump house. This caused a noise in a new location between the pool and the pump house as well as in the previous place between the skimmers. Since there was only one place where a leak noise was heard from all three induction points, we determined that was the leak location.

Because we were unable to get all the water out of the line there were also misleading sounds caused by air traveling through water trapped in low spots of the plumbing. By comparing leak noise locations as we changed the induction points, we could decipher which noise was the leak noise and which noises were false positives. Under pressure, air will only travel as far as it must in order to escape through the leak, so the low spots in the plumbing did not make noise unless they were between the induction spot and the leak location.

The extra listening time paid off – once the concrete was cut, we could see that our leak location was spot on! During the repair the lines were pressure tested to ensure that the other noises we had heard were not also leaks. While inducing air from multiple locations takes time, it’s still faster and more accurate than other methods that require you to fish equipment through the plumbing lines. Plus, due to the long plumbing run a camera wouldn’t have been able to reach the entire line and the amount of tracer gas needed to fill the line would have been expensive.


  1. Pressurized air escaping into water saturated soil makes a clear noise that can be accurately located with a listening device.
  2. Once pressure is built up, air in a pipe will only travel as far as it must to reach the leak, not further.
  3. Changing induction points can help rule out false noises from water stuck in low spots of the plumbing.

Pressure Testing Principles


You may know that it’s best to use water to isolate leaking plumbing lines with a pressure test, but do you know why? Check out this video to learn about the pressure testing principles that describe how water and air interact in pool plumbing, and how that impacts your tests to find plumbing leaks.


  1. Air compresses under pressure, water does not.

This is the primary reason why we recommend using water for a pressure test instead of air. If air and water are both present in the plumbing line during a pressure test, the air will compress under pressure and can slow down the pressure drop you see on your gauge. On a long run of plumbing this can reduce the pressure drop to an imperceptible amount, making a leaking pipe look like it held pressure.

  1. Air escapes from a leak faster than water does.

You will see a much faster pressure drop when air escapes from a leak than when water does. If you’re trying to get air to a leak to be able to start pinpointing the leak with a listening device, watch for a dramatic drop in pressure. Once this happens you’ll know that air has reached the leak and you can start listening for the telltale bubbling/gurgling noise.

  1. Water stays low in the plumbing line, air stays high.

Water and air do not stay “mixed” in a plumbing line – the water will always go to the bottom of the plumbing and air will stay high. Even if both water and air are induced at the same time they will separate in the pipe. You won’t make a good leak noise if the leak is in a low part of the plumbing and all of the water above the leak has not been purged.  Additionally, you can create distracting noises where air bubbles through water if you’re inducing pressure from the low end of the plumbing.

The Bottom Line

There are two parts to finding leaks in swimming pool plumbing – isolating the leaking line with a pressure test and pinpointing the leak by listening through the pool deck. For effective pressure tests, make sure the line is entirely filled with water. When you’re ready to start listening, make sure that air is reaching the leak in order to make a clear noise.

For more detailed information about pressure testing and sonic pipe leak location, see the corresponding slideshows in our Resource Center. These slideshows provide an in depth explanation of the process and tools used for each test using text annotations and graphics. Don’t hesitate to call us at 800-348-1316 if you have any questions about the material!

Case Study: Above Ground Pool With Multiple Leaks


Type of Pool:

Above Ground, Vinyl Liner

Equipment Used:

LeakTrac 2400Dye Testing Cones, Pressure Testing Equipment


Pool owner noted water loss of 1.5” per day and hinted that they thought the liner needed some patching.


Since the LeakTrac 2400 can pinpoint liner leaks in above ground pools too, we started by doing a liner scan. It can be a little harder to find a good ground source on above ground pools, but at this pool we were able to attach to the steel wall, which gave us a great connection.   We promptly located and patched a small liner leak under the ladder. It didn’t seem to be big enough to be responsible for 1.5” per day of loss, so we kept looking.

Since the liner was eliminated from being a source of water loss with the LeakTrac, we set up the Dye Testing Cones to do a static dye test of the plumbing, which revealed a potential leak in the return line.  A failed pressure test of the return line confirmed it was leaking.  This was sort of peculiar since the line was primarily visible and dry.  Once air was induced, we noticed it  bubbled up through the rocks in the short area the line was actually underground. In a little over an hour we had found and patched the liner leak and pinpointed the pipe leak.


  • The LeakTrac 2400 works great on above ground vinyl liner pools, you may just have to get creative with your ground connection.
  • It’s easy to pinpoint leaks in pipes that are close to the surface, just keep your eyes open!

Finding Leaks In Green Pools

When performing a leak job there are certain pool conditions that are important to have in place when you get to the job site.  The pool should be filled to normal operating level, and it’s best if the water is clear, clean, and warm.  Of course, even with prior communication things aren’t always ideal. So, what do you do if you arrive at a pool that’s cloudy or green?

In many cases it may be best to just walk away.  Simply put, you can’t see through green water and anything that requires visual observation will be compromised. The chances of success in locating and repairing a leak go down if there is a problem with visibility. Plus, you need to be careful about health risks and equipment damage when working on green pools. So even though you’ve already invested time in just getting there, it’s frequently best to have the customer clear up the pool and schedule a time to come back.

With that being said, cleaning up a green pool before a leak detection appointment can be a difficult  or unreasonable task. Especially because it’s common for leaking pools to be green because they are leaking – it’s hard to maintain chemical balance when you’re consistently adding untreated water to the pool. So, if you have no choice but to work on a green pool, here are a few tips to keep in mind.

Sometimes the water is actually clear but algae is covering the shell surface.  In these cases look for a spot that has no algae.  The water movement of a leak often washes out the algae in that area.  This can make for a quick and easy job!

Algae is washed away around leak. There is also a stick stuck in the leak.

If the water is so green that you can’t effectively do any dye testing, electronic equipment that doesn’t require you to get in the water. Both the LeakTrac and hydrophones can be used, as long as they are cleaned off immediately afterwards.  Pressure testing  and pipe leak location can also be done. Keep a pair of stay dry gloves on hand to keep your arms algae free when putting in plugs.

One of the most important things when dealing with unfavorable conditions at a pool is to set clear expectations for the job.  If you do have to perform work on a green pool, let your customer know that your efficiency and effectiveness may be impacted but that you will still be charging for your time.

Listening For Plumbing Leaks With A Hydrophone

Even if you’ve made a good leak noise and are using your electronic listening device filters correctly to pinpoint the location of a plumbing leak using a deck microphone, you may want to use your hydrophone attachment from within the pool to get an additional angle on these plumbing leaks. If the leaking pipe is close to the pool wall, or in a main drain line under the pool, the bubbling noise of air escaping from the pressurized pipe can be heard with your hydrophone through the pool wall. Using a hydrophone is a great way to double check or verify the location you identified from pool deck or help hone in on a leak noise that spans a large area.

Leak technician using hydrophone to listen through pool wall

Because you’re often able to get so close to the leak when listening through the pool wall, the digital readout on your Fisher electronic listening device is especially helpful for this use. There will typically be a more definite high point in the volume readout, which can be more accurate than just relying on your ears to determine the loudest place.

Based on our experience, this method of using a hydrophone for pipe leaks has proven to be much more effective than listening for problems from inside the line.  Trying to get the hydrophone into pipes past T’s and elbows is time consuming (if not impossible), and unpressurized leaks may not even make a perceptible noise.  Knowing how to use the right tool at the right time is an important way to make your leak detection jobs efficient and accurate.

Open Inflatable Plugs: 550Q vs 550BP

Trying to decide between the 550BP and 550Q open inflatable plugs? These plugs both provide a versatile solution for inducing pressure into 1-1/2″plumbing, but it can be hard to know which style is the right choice for your application.  Each plug includes a tire valve attachment for inflating the plug itself and a male quick connect attachment for inducing pressure into the plumbing with your pressure tester, but the way they’re structured is different. Read on to learn about the key differentiating features.

550Q (Q-Ball):

550Q Open Inflatable Plug

The most prominent feature of this plug is that the inflation and induction attachments are on the end of 2’ hoses, which allows the plug to be lodged farther into plumbing. It can be pushed past valves, through pumps, or past threads on return fittings. Also, the bypass tube that runs through the plug for inducing pressure is made of flexible rubber, so the plug can be bent in order to move around 90 degree elbows or other tight spaces.

The bypass tube on this plug is small, which means it takes a longer time to pressure up lines when using it. Since it’s also flexible it can be pinched when the plug is over-inflated and prevent air/water from flowing freely.



550BP open inflatable plug

The biggest benefit of this plug is that the bypass tube is made of metal instead of rubber. This allows water or air to pass through the plug at a higher volume, which saves time and produces clearer pressure testing results. The induction attachment is an “L” shaped quick connect right off of the top of the plug, which works especially well in pump bowls and valves. Both the flexible inflation hose and quick connect are attached to threads on the top of the plug, so they can be replaced with longer air or inducer hoses for added versatility.

550BP open inflatable plug with CPH18
550BP-CPH plug with L-shaped quick connect replaced with an 18″ inducer hose.


The connections between the rubber and metal bypass tube on this plug are slightly weaker, so these plugs are more susceptible to wear and tear.

In general, inflatable plugs are more delicate than their mechanical, wing nut expanded counterparts. Their versatility and convenience make them an attractive option, but if you’re looking for a more durable, less-expensive solution, mechanical plugs are preferred. For 1-1/2” pipe the O45 Standard Open Plug or O45E Open Extender Plug can be used.

Common Signs Of A Leaking Pool

Water loss is the most obvious sign of a leaking pool, but are you able to recognize the other common symptoms? Watching out for these signs at your customers’ pools can help them get ahead of further damage and puts you in the position to he the hero that can solve the problem!

infographic showing the common signs of a leaking pool

1. Water Level Changes

Dropping water level is the clearest sign a pool is leaking, but it’s important to determine if the water loss is due to evaporation or a leak. Evaporation rates vary depending on wind, air and water temperature, humidity, and other factors. Use our Evaporation Calculator to see the evaporation rate in your area based current weather data. Water loss in excess of that amount indicates that the pool is leaking.

2. Cracks or Falling Tile

Because the surrounding ground is becoming unsettled by the presence of excess water, cracks and tile movement are more likely to occur when a pool is leaking. Cracks or gaps in the bond beam may occur as the pool settles farther into the softened ground.

3. Wet Spots in Yard

Soft, mushy spots or uneven grass growth around the pool area may indicate a plumbing leak. Erosion due to water movement underground can cause landscaping to shift and sink.

4. High Water Bills

Automatic fill devices can hide leaks by keeping the pool filled. If you notice the autofill running constantly or increased water bills it’s time to start investigating for a leak.

5. Water Under Equipment

Standing water or corrosion at the pump or around pipes is a sure sign of a leak. Equipment leaks can often be found with just visual inspection.

6. Air or Dirt Blown Into Pool

If air or dirt is being pulled into the plumbing system through a leak, you may see that air or dirt being blown into the pool from the returns. This may also cause mysterious gurgling sounds.

7. Algae Growth

Continually adding new, untreated water to a leaking pool often leads to fluctuating chemical consumption and algae growth or discoloration. Instead of continuing to treat the water, finding and repairing a leak may be the solution.

Listen to Anderson Manufacturing on the Pool Chasers Podcast!

We recently hosted Tyler and Kyle from the Pool Chasers podcast at our headquarters in St. Paul, MN to share a glimpse into our business and teach them about leak detection. After a day of training, they sat down with Lance (Owner) and Brad (Technical Sales Manager) to have a conversation about the history and values of our company as well as more tactical information about how to succeed in swimming pool leak detection. As a sponsor of the podcast we’re happy to be supporting Pool Chasers on their mission to educate and inspire the pool industry.

You can listen to the podcast on their website here or on Apple Podcasts, Google Play, Spotify, YouTube, Soundcloud or Stitcher.

four men at table recording podcast

Case Study: Misleading Dye Test

Type of Pool:

Vinyl Liner

Equipment Used:

Dye Tester Cones, Pressure Testing Equipment, Electronic Listening DeviceLeakalyzer

Pool with leak detection equipment


Customer reported that pool was losing water and suspected the skimmer line.


Based on the customer’s suspicion we started out leak job by running  a dye test of the skimmer lines right away using the dye testing cones. The deep end skimmer was plugged while the shallow end skimmer was tested and vice versa. Both skimmers pulled dye.  Since each skimmer had its own run from the pump, and since we had isolated each line by closing valves we thought that both lines had a leak.

In order to start pinpointing those leaks, we first pressurized the line with air from the deep end skimmer back to a closed valve at the equipment. We could immediately hear the bubbling noise of air escaping into water saturated soil right below the skimmer bowl.

Then, we checked the shallow end skimmer line by switching to inducing pressure from that skimmer bowl. There was no noise and a much slower pressure drop. After listening for a while but still not finding a noise and not seeing a significant pressure drop, we switched to inducing pressure from the valves to isolate each line individually. Using this approach the shallow end skimmer line held pressure and the deep end line made noise in the same spot we had heard before.

Pressure testing from pool equipment

It turns out that the shallow end skimmer line was not leaking, but it had drawn dye through the pipes to the other skimmer break due  valves that didn’t seal off properly. Pressure testing helped us determine that there was just the one leak, not two.

We also ran a Leakalyzer test on the shell of the pool while the lines were plugged.  The results confirmed that the pool shell wasn’t losing water. We left the job having given the customer a clear leak location and the assurance that their pool would no longer be leaking once the plumbing repair was made.


  • Leaks can siphon through bad valves, which produces unclear results when dye testing. It’s important to understand how your tests may give deceptive information and perform secondary tests if you are left with any uncertainty. Pressure testing was able to verify the line was good despite drawing dye.
  • Opening the pump lid would have been an effective method of isolating the skimmers by creating an air break. Since the dye test was done early in our Initial Assessment we hadn’t yet opened the pump.

Understanding “No Water Loss” Leakalyzer Tests

While Leakalyzer tests that show water loss are extremely valuable for more efficiently locating leaks, using the Leakalyzer to identify when no water loss is happening is just as valuable.  One of the biggest wastes of time for a leak detector is trying to find a leak that doesn’t exist. But, leaks aren’t the only factors that cause a change in water level, and homeowners can be quick to call for help without considering the other factors that may be at play. In these situations the Leakalyzer can help confirm if in fact the pool is leaking before starting work. Or, once a leak has been found and repaired, a no water loss test can confirm that your repair is holding and that no other leaks are present.

Even though it seems like reading these tests should be straight forward, the Leakalyzer is so sensitive that minuscule changes in water level that are smoothed out during a water loss test show up more significantly on a no water loss test, making the trend harder to identify. The spikes that show up on the graph in these situations don’t mean it’s a bad test, they just show that the Leakalyzer is being extremely accurate. Because of the movement in pools, the water level is constantly going up and down slightly. Remember, the Leakalyzer is able to measure water level changes down to the 10,000th of an inch (the size of a red blood cell!), so you’ll see these tiny changes on your graph.

When looking at the graph, the ability to identify trends is the key to effective use and interpretation. You’re trying to look past the up and down spikes to identify if as a whole they are trending flat or downward. For instance, if you are 10 or 15 minutes into the test and still consistently spiking on either side of zero or the evaporation mark it is most likely a no water loss situation. However, if the test is going up and down but both the highs and the lows are consistently getting lower there is most likely a leak.

Another aspect to watch is the scale of the graph.  The scale automatically adjusts based on the measurements that the Leakalyzer is recording. Sometimes when the pool isn’t losing water, the ups and downs on the graph can look drastic, but the scale of the graph is still at 0 to 30. This makes for very dramatic spikes with very little actual change in the water level.  Zooming out to a 120 or 240 scale causes those spikes to look more realistic, and will help identify a flat line trend.  Remember, a measurement of 100 on the scale is only equal to the thickness of a sheet of paper! Take a look at the below graphs to understand how the scale affects no water loss tests.

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