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Case Study: Long Plumbing Run with Multiple Leak Noises

 

Type of Pool:

Concrete – Commercial Pool

Situation:

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.

 

Solution:

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.

Highlights:

  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

Situation:

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

Solution:

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.

Highlights:

  • 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!

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

Benefits:
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.

Drawbacks:
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:

550BP open inflatable plug

Benefits:
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.

Drawbacks:

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.


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

Situation:

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

Solution:

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.

Highlights:

  • 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.

Case Study: New Pool, Big Leak

Type of Pool:

Vinyl Liner

Equipment Used:

Leakalyzer, LeakTrac, Dye Tester Cones, Pressure Testing Equipment, Electronic Listening Device, Hydrophone, Tube Level

Situation:

We were called to examine a new build that was losing 4” of water per day. It hadn’t been leaking for the first four days that it was filled but recently started rapidly losing water. When we arrived to the pool the water level was down below the skimmers, but the skimmer bowls were still full of water – indicating that those lines were not leaking.

Solution:

Suspecting that the problem was in a plumbing line, we did a quick dye test of the returns and cleaner line with the dye testing cones, but they also were not drawing water. Our Leakalyzer test had been running during these initial observations, and indicated a loss of 3.5 inches per day. A quick scan with the LeakTrac showed no leaks in the liner, so it was time to dive down to the main drain. A dye test with the dye testing cones showed that line was the source of our water loss.

We then plugged the main drain lines while we were diving and ran a pressure test from the equipment back to the pool. The water pressure test confirmed the line was leaking, so we then started inducing air for sonic location. It took a while for the air to reach the leak, indicating that the leak wasn’t close to the equipment where the air was being induced. So, we used a hydrophone attached to our XLT30H listening device to start listening along the main drain lines where they ran close to the shell of the pool. We could hear the loud bubbling/gurgling noise of air escaping into water saturated soil near the base of the wall in the middle of the deep end.

Since the main drains were plugged we ran another Leakalyzer test to verify that the rest of the pool shell was not losing water and the main drain line was the only issue.

A main drain leak at the base of the wall is not a repair anyone wants to make, so to verify the sonic leak location we used a tube level. We attached a clear plastic tube to the end of a standard open plug in the main drain. Now, instead the leak draining water from the pool it drained the water in the tube. The tube leaked down to the level of the leak and then stopped. We colored the water in the tube with Leakmaster Fluorescent Dye to be able to clearly see the water level. The water level stopped right at the level that we had identified with the hydrophone.

The crew dug up the leaking plumbing line and found a stake had been driven through the pipe!?!

Highlights:

  1. A hydrophone with digital sound graph is helpful when listening for main drain plumbing leaks through the shell of the pool.
  2. The Leakalyzer helps verify the rest of pool isn’t leaking while pressure testing and pinpointing leaks in plumbing.
  3. A simple tube level can help verify the depth of the leak before digging. Be creative with the materials you have on hand!

Case Study: Not What We Suspected

Type of Pool:

Vinyl Liner

Equipment Used:

Leakalyzer, LeakTrac 2400, Pressure Testing Equipment, Dye, Leakmaster Pool Glue

Situation:

We were at least the second company to take on this job, so the homeowner was concerned about how we could be sure that all the leaks were found. She was also convinced that the leak was in the return side plumbing.

Solution:

We started pump on/ pump off test with the Leakalyzer and found that the pool was losing more water with the pump running. This usually tells us to suspect pressure side plumbing.

We had two techs on this job, so one tech began running a pressure test while the other ran a vinyl scan with the LeakTrac 2400.  The pressure test on the pressure side plumbing held, but the LeakTrac was getting a stronger than normal signal coming from the skimmer.  We did a quick dye check of the skimmer and  sure enough the bottom of the skimmer bowl was cracked. The movement of water in the skimmer, or possibly even a slight shift in the suction pipe when the pump was running caused more water loss.  This was a rare situation where higher water loss with the pump running wasn’t an indication of a pressure side leak.

We repaired the skimmer bowl with Leakmaster Pool Glue and fiberglass mesh, which provides a permanent repair that will be able to handle the movement of the pool as time goes on. We charged the homeowner an additional fee for this repair. Once the repair was done, a final Leakalyzer test confirmed the now repaired skimmer leak was the only leak.

Highlights:

  1. Remember that pump on/pump off tests only provide suspicions of where the problem is.  Further tests are needed for confirmation.
  2. LeakTrac can indicate a leak in the skimmer with higher than normal intensity.
  3. Count on your own observations, diligence and reason more than what other people tell you.

Case Study: A Job Done Right Pays Off

Type of Pool:

Concrete – Commercial (Apartment Complex)

Equipment Used:

Leakalyzer, Pressure Testing Equipment, Hydrophone, Dye, Dry Suit, Super Snorkel

Situation:

After opening the pool for the summer the customer noticed significant water loss and gave us a call. When we arrived to the job the Leakalyzer reported nearly 6” of water loss per day.

Solution:

The first two leaks were found right away while we were gathering information. One was clearly visible while we were inspecting a return fitting and the other was found around an equalizer line while we were scanning the pool with a hydrophone. We were able to repair both leaks with Leakmaster Pool Repair Putty.

After the initial leaks were repaired a new Leakalyzer test reported 2.35” of water loss per day. We used dye to find two more leaks – one at another return fitting and one at the tile line.

Once these leaks were repaired the Leakalyzer was still reporting a loss of 1.84” per day. So far we had found and repaired four leaks but were still losing a significant amount of water. We ran a quick pressure test to eliminate the plumbing as the source of the remaining water loss.

Finally a crack in the tile line deeper down in the pool was found and fixed getting us to a no water loss test. Five leaks found, five leaks repaired. Between the multiple Leakalyzer tests, pressure tests, electronic microphone use, extensive dye testing and even diving in freezing spring water this job was more work than most. Once it was all said and done we felt good that we didn’t just solve one of their problems and move along. The property manager was thankful and eager to get us set up as a vendor for all their properties. They even mentioned that we’d done more than other companies had ever done.

Highlights:

  1. Large leaks in concrete pools can be found with a hydrophone, but it may not pick up smaller leaks.
  2. Using the Leakalyzer throughout the job meant we were there longer finding additional leaks, but it saved us from a costly callback.
  3. Extra effort and a job well done gets noticed and helps drive future business.

Case Study: Eliminating Misleading Leak Sounds

Type of Pool:

Vinyl Liner

Equipment Used:

Leakalyzer, Pressure Testing Equipment, XLT30HHydrophoneDye

Situation:

Customer reported that the pool was leaking 1-2 inches per day and that a new liner was installed recently. When we arrived, the pool level had already dropped below the skimmers and returns.

Solution:

We ran a pump on and pump off test with the Leakalyzer and found the pool was losing slightly more water with the pump off. This indicated that we should suspect suction side plumbing. Since the pool water level was already below the skimmers we dove down to check the main drains. A dye test confirmed that the main drain line was drawing dye from both of the two main drains.

We set up our pressure testing equipment to start pinpointing the location of the leak and ran a quick pressure test with water first to confirm that what the dye was showing was accurate. Once we started inducing air and purged all the water from the line we were able to hear a good leak noise in two spots with the Hydrophone (attached to the XLT30H). The first noise was right at one of the main drain bowls and the other was in a corner of the pool. While we had the main drain lines plugged we also ran another Leakalyzer test, which verified the water loss had stopped in the pool so there was no need to run a LeakTrac on the liner or dye test the fittings, skimmers, etc.

In order to determine which noise we were hearing was actually the leak, we slid an inflatable plug 8’ into the line from the main drain bowl and re-pressure tested. The pressure test still failed, so we knew the leak had to be farther than 8’ away from the main drain bowl. With this information we decided that the place we heard noise in the corner of the pool was the leak location. Another confirming factor was that while we were inducing air, there would occasionally be a bubble that came up behind the liner to the surface of the pool. Before leaving we also ran pressure tests on skimmer and returns to verify the rest of the plumbing was good.

Learnings:

  1. Pressure testing helped us identify actual problem when the  noise was heard in multiple locations.
  2. Leakalyzer verified that pool shell was leak free, saving us time during the isolation phase.

Case Study: Persistence Pays Off

 

Type of Pool:

Gunite Spa/Pool

Equipment Used:

LeakalyzerXLT30H, Hydrophone ,Dye, Ridgid Inspection Scope,  Ridgid Micro Drain Reel, Pressure Testing Equipment, Dye Testing Cones

Situation:

The customer called because their pool would leak down to the tile line and stop, so they wanted us to locate the leak and asses the tile line to determine if a full renovation was needed. When we got to the pool the water level was filled to the normal level as we requested, but the customer pointed out where it would typically leak down to which was an inch below the skimmer, but a couple inches above the jets. It seemed as though we were in for a quick tile line crack location and putty repair.

Solution:

We ran a Leakalyzer test to get a better understanding of how fast the pool was losing water and while doing so started listening with a hydrophone to the suspected tile line. A quick trip around the pool with the hydrophone didn’t uncover any suspect areas. We moved on to dye testing because sometimes small leaks don’t make enough noise for the hydrophone. After dye testing the whole tile line we were able to confirm that there were no leaks in the shell of the pool at the level where the water drained down to. It turns out this job was going to be a little more complicated than we thought!

We checked our ongoing Leakalyzer test which was showing a current rate of over 20” per day of water loss (small pool, big leak). To do a quick check of the plumbing lines we used the Dye Tester Cones and learned that the jet returns drew dye like crazy. Because the water level stopped higher than the jets we began to suspect the blower line instead of the jet return line. A pressure test confirmed the suspected line was leaking as we couldn’t even build any pressure. A Leakalyzer test with the jet returns plugged confirmed the rest of the pool was not losing water, so we knew we could be done with any further testing in the shell of the pool.

Since the equipment pad was positioned lower than the pool, in order to induce air from the high side of the plumbing we had to use one of the jet returns. When we started listening with the XLT30H there was a loud noise right above where we were inducing pressure that actually seemed to echo throughout the pool. There were two places that seemed louder and more distinct than the other areas though: the jet fitting and a place where the pipes presumably ran underneath the pool. We deduced that even though we were inducing from the high side of the plumbing, since the leak was in the blower line the air had to travel through remaining water in the jet line, creating some of and perhaps all the noise we were hearing. To confirm this suspicion, we switched and induced pressure from the other side of the plumbing. After this switch the sound in those two locations went silent. This confirmed we were hearing the sound of air traveling through remaining water in the pipe and not air escaping out of the leak into water saturated soil.

The lack of noise around the pool forced us to look closer to the equipment which would mean that the leak had to be well below where the water level stopped.  It turned out there was a Hartford Loop for the blower line, but it wasn’t high enough and thus didn’t stop water from draining back through until the water level reached the familiar point on the tile.  We suspect someone made a modification to the blower plumbing at some point for aesthetic reasons and buried the loop without understanding its purpose.

Building enough pressure for a quick sonic location was difficult and since we had easy access to the flexpipe  we used a Ridgid Micro Drain Scope and a line locator to pinpoint the exact location. About 15 feet in we saw what appeared to be a cracked pipe due to freeze damage.

To verify the crack we saw was our leak, water was induced into the blower line from the high side of the plumbing and we pulled that camera back towards the low side of the plumbing watching for the water flow to stop.  Sure enough the water was flowing into this crack.  The crack was dye tested with extension tubing from Anderson Manufacturing affixed to the end of the camera. The dye was drawn into the crack a well. The crack was about 8’ long and on both sides of the pipe – so no wonder we couldn’t build pressure!

Learnings:

  1. Just because water stops at the tile line doesn’t mean it’s the tile line that’s leaking!
  2. Inducing pressure from both ends of plumbing can be a way to verify if you’re hearing a leak noise vs air traveling through water in pipe. If noise is only audible when you induce from one end it may be standing water in the pipe not air escaping into water saturated soil.
  3. Dye Tester Extension Tubing can be taped to inspection cameras for leak verification or location.
  4. Persistence paid off, but this one was a bit misleading and ended up being time consuming. Some leaks are more tricky than others!

 


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