Damage To Your Swimming Pool

It would seem that if you are experiencing water loss, a likely suspect would be any aspect of the pool which appears to specifically be in disrepair. If one corner of your liner is duct taped to repair a tear in the liner, you likely have found the culprit.

Should any noticeable inconsistencies in the liner exist, whether on the walls or the floor, this would be well worth noting. Inconsistencies in the wall and floor can be either the direct problem, or a symptom thereof so heavy scrutiny should be given to any area of the pool, which appears to be abnormal.

Start In The Pool Pump Room

The pool itself will be relatively easy to inspect for damage. The plumbing system which is largely buried below ground is much more difficult to inspect. The pool mechanical or pump room will be a good place to get a look at the type of plumbing that was used in the construction of your swimming pool.

You are looking for any signs of leaks, but you are also viewing the quality of the plumbing installation, the type of plumbing materials used, and the relative condition of these materials.

If you have a plumbing system that is very old and appears to be installed in a haphazard way you would rate the possibility of a leak in your plumbing system higher than a swimming pool mechanical room which looks like it was installed yesterday. Another example would be to check the type and condition of any pipe clamps, which are used with black polypropylene piping material.


Pipe Clamps Are A Huge Leak Source

Pipe clamps should be compromised of stainless steel and should be free of rust and decay. Additionally these clamps should always be installed in tandem, meaning that two clamps are tightened over each fitting.

Again, you are not looking for definitive causes for the water loss in your swimming pool just yet, but instead creating a profile of your swimming pool, which will allow you to follow a logic system to systematically determine the location of the leak in your pool.


Gaskets & Faceplates

In a vinyl liner swimming pool you should inspect all gaskets and faceplates in the returns, skimmers, in-wall stairs, lights and any other location where a compression seal is made around a hole in the vinyl liner. Should obvious signs of rust be present on the faceplate itself or the screw heads that would increase the likelihood of leaks in these locations


Pool Damage Inspection Conclusions

If visible damage exists on any part of your swimming pool you can consider this location a high likelihood for water loss. Still, only so much information can be garnered from a simple inspection and you must further analyze the pool leak characteristics in order to gain a full understanding of where your pool is leaking, and how to fix it.



Pool Leak Characteristics

Worth noting is the insight that you may have as the owner of the pool. If the leak developed shortly after having construction done on your property, or heavy landscaping around the pool area, or a wild party with broken glass on the pool deck, these could all easily help to determine the likely location of the problem.

In fact, the history and characteristics associated with the leak in your swimming pool is likely the single biggest factor that can help you to locate and identify the leak source. Being able to monitor the tendencies of the leak and what affects the rate at which your pool loses water can often alone point you in the direction of the leak location.


Monitor Your Water Loss

The importance of maintaining a leak rate schedule for your pool can not be understated and this is true whether you are fixing your own pool or hiring a pool service professional to do the job for you.

How and why your pool leaks under different conditions is a complicated subject. Arming yourself with as much information as possible will help to increase your chances of fixing your own swimming pool leaks.

Assuming that no one jumped their bicycle into the pool recently, and you keep glass shattering pool parties to a minimum, a likely candidate for sudden water loss issues could be the pool plumbing systems.



Pool Plumbing Systems

The basic configuration of a swimming pool plumbing and filtration system is simple. Water is pulled through the skimmer and main drains in the swimming pool by the pool pump. The water travels underground back to the mechanical room where it passes through the pump strainer basket and is then pushed through the filter and heater as well as any other peripherals such as chlorinators, and is eventually piped back to the pool through the return lines.

In addition to these closed system lines, there are also a few additional aspects to the swimming pool plumbing system, which do not operate, in a closed (pressurized) system. Most swimming pools employ an open system (gravity fed, not pressurized) equalizer line that helps the pool pump to retain its prime during periods of low water level. This equalizer line is often forgotten about or ignored during renovations as replacing the line is a costly and time-consuming enterprise.

The equalizer line will connect to the bottom of the skimmer and the other end to either the main drains, or a side port in the wall of the pool near to the location of the skimmer. It is the pipe that leads from the bottom of the skimmer down to the main drains that is often overlooked. Since this is a non-pressure line it would tend to leak less than a pressurized line, but on average this pipe can also be older than the rest of your pool plumbing system increasing it as a candidate for unexplained water loss.

Plumbing systems are a constant source for water loss for a host of different reasons ranging from pipe material, installation quality, and age, configuration and soil conditions. Before you begin to tear apart your plumbing system you need to first isolate the leak to be located in the plumbing system, or in the structure of the pool itself. To begin diagnosing the locations of the leak in your swimming pool proceed to the hydrostatic diagnostic test.



Swimming Pool Leak Detection

This simple leak detection test can be preformed by absolutely anyone with minimal effort, yet the results from this test are incredibly important in locating the leak in your pool. By closely observing the pool under different conditions and recording the results for comparison, you will have the ability to more accurately and efficiently solve your leaking pool problem.

Hydrostatic Leak Detection Test

To determine if the water loss problem is in the plumbing system of the pool, or in the pool structure itself you will need to monitor the water loss over given periods of time in a log book. Start by filling up your swimming pool and marking the water level line with a PENCIL on the faceplate on the mouth of the skimmer. Be sure to let the water settle before making your mark to get an accurate reading. Note the exact time that you filled the pool in your logbook.

Next, simply let the pool run as per normal for a full 24 hours and then mark the new water level on the face of the skimmer. You will now be able to measure the amount of water loss with a ruler or tape measurer.

Fill the pool back up and mark your water line again being sure to erase the previous marks to avoid confusion in the future. This time you will turn off the plumbing system for the 24-hour period and then measure the total water loss again.


Find Out Where Your Pool Leaks

Be sure to factor into consideration extreme weather such as heat or rain that could easily negate the validity of your test results. If your measurements are in question, repeat the process to achieve accurate test results. Once you have completed the test you will be able to process this data to help you fix your leaking swimming pool using the hydrostatic test conclusions.

A swimming pool will run between 5 and 30 PSI on average. Ideally the plumbing lines will be tested at a level above the maximum operating pressures to ensure that there are no leaks in the system. The concern with this is that pressure testing any system over a few PSI can be dangerous so many testers prefer to test at lower pressures such as 5, 10 or 20 PSI. In theory a plumbing leak will be apparent under all pressurized situations but this is not always the case with elusive leaking problems. It is recommended to test at a higher pressure that the normal operating values of the plumbing system.



Hydrostatic Test Conclusions

If the water loss is the same whether the plumbing system is running or not, you will likely find the leak to be in the structure of the pool itself, and likely not in the plumbing system. This is not to say that you would simply discount the plumbing, as swimming pools can often be elusive in terms of diagnosing unexplained water loss. This is to say that you will begin your search by focusing more on the structure of the pool.

Should your test results indicate a difference in rate of water loss when the plumbing system is running and when it is shut off, this can be a strong indicator for a problem existing in your plumbing system. You cannot discount the possibility of a structural pool leak, but provides you with an initial direction to begin your water loss troubleshooting.

If you have a pool leak problem that prevents you from conducting this experiment due to drastic water loss conditions, you can monitor water loss for longer or shorter periods of time to accommodate the leak rate of your pool. Also note that weather conditions can skew the validity of your test findings so be sure to repeat the process if the results are in question.

Having the first test completed, you now have some hard evidence, which will help you to narrow in on the water loss problem. A pool professional will begin to formulate a diagnosis of your pool with this information, not a clinical diagnosis, so much as a general intuition based upon recurring problems which are documented time and again in the industry.

Choose your water condition from the menu on the right. Each condition is defined if you hover over the condition tab.


Leak Test Condition 1

Leak condition 1 refers to the pool losing the same amount of water whether the pump system is on or off. Based upon the leak characteristics displayed by your swimming pool during the hydrostatic leak test, here is a list of the more likely areas of concern for your pool. This information is not sufficient for stand alone diagnosis of your swimming pool leak in most cases, but can very often lead to an efficient diagnosis and repair due to recurring instances of these common pool failures:

(Small leak of less than 1” / 2.5cm per day)
-possibly a small hole in the liner, likely on the wall -leaking around gaskets such as stairs, skimmer mouth, lights etc -hole in liner under drop in ladder resting position

(Medium leak of 1-3” / 2.5-7.5cm per day)
-Major hole in liner, specifically on the floor of the pool -Failing hydrostatic relief valve in main drain -Failed gaskets at stairs, returns, lights or skimmer -Cracked equalizer or non-pressure pipe

(Large leak of more than 3” / 7.5cm per day)
-Hydrostatic relief valve in main drain stuck open -Liner seam separation -Broken equalizer line


Leak Test Condition 2

Leak condition 2 refers to the pool leaking more when the plumbing system is on, but water loss is experienced in both conditions. Based upon the leak characteristics displayed by your swimming pool during the hydrostatic leak test, here is a list of the more likely areas of concern for your pool. This information is not sufficient for stand alone diagnosis of your swimming pool leak in most cases, but can very often lead to an efficient diagnosis and repair due to recurring instances of these common pool failures:

(Small leak of less than 1” / 2.5cm per day)
-Crack in return line -Loose fitting connection on return line -Pump seal missing or damaged -Filter head gasket out of alignment

(Medium leak of 1-3” / 2.5-7.5cm per day)
-Broken fitting on return line -Lengthwise pipe crack on return line -Filter head gasket out of alignment

(Large leak of more than 3” / 7.5cm per day)
-Severed return line -Crushed pipe -Filter head gasket out of alignment -Multiple return line leaks


Leak Test Condition 3

Leak condition 3 refers to the pool leaking more when the plumbing system is off, but water loss is experienced in both conditions. Based upon the leak characteristics displayed by your swimming pool during the hydrostatic leak test, here is a list of the more likely areas of concern for your pool. This information is not sufficient for stand alone diagnosis of your swimming pool leak in most cases, but can very often lead to an efficient diagnosis and repair due to recurring instances of these common pool failures:

(Small leak of less than 1” / 2.5cm per day)
-Filter head gasket out of alignment -Loose fitting or crack in suction line

(Medium leak of 1-3” / 2.5-7.5cm per day)
-Filter head gasket out of alignment -Loose fitting or crack in suction line -Multiple leak locations

(Large leak of more than 3” / 7.5cm per day)
-Filter head gasket out of alignment -Broken fitting or broken suction line -Multiple leak locations


Leak Test Condition 4

Leak condition 4 refers to the pool leaking when the plumbing system is on, and not leaking when the plumbing system is off. Based upon the leak characteristics displayed by your swimming pool during the hydrostatic leak test, here is a list of the more likely areas of concern for your pool. This information is not sufficient for stand alone diagnosis of your swimming pool leak in most cases, but can very often lead to an efficient diagnosis and repair due to recurring instances of these common pool failures:

(Small leak of less than 1” / 2.5cm per day)
-Small crack or loose fitting on return line -Leak in the pump, filter or heater -Filter head gasket out of alignment

(Medium leak of 1-3” / 2.5-7.5cm per day)
-Broken return line -Filter head gasket out of alignment

(Large leak of more than 3” / 7.5cm per day)
-Multiple return line leaks -Filter head gasket out of alignment -Broken fitting or pipe in return line


Leak Test Condition 5

Leak condition 5 refers to the pool leaking when the plumbing system is off, and not leaking when the plumbing system is on. Based upon the leak characteristics displayed by your swimming pool during the hydrostatic leak test, here is a list of the more likely areas of concern for your pool. This information is not sufficient for stand alone diagnosis of your swimming pool leak in most cases, but can very often lead to an efficient diagnosis and repair due to recurring instances of these common pool failures:

(Small leak of less than 1” / 2.5cm per day)
-Crack in skimmer suction line or fittings

(Medium leak of 1-3” / 2.5-7.5cm per day)
-Crack in skimmer suction line or fittings -Crack in the main drain suction line

(Large leak of more than 3” / 7.5cm per day)
-Broken suction line or fitting


Another Easy Leak Detection Test

Fixing a leak in your swimming pool is a process of gathering information and identifying specific areas of your pool prone to leaks. For each piece of knowledge you acquire from the testing that you are doing you are taking a small step towards isolating the exact problem.

The information will also allow you to eliminate less likely leak points from your search. You will not often interpret data from any one test and be able to say exactly where the problem exists. You may however be able to determine where the problem is likely NOT to be from any one test. With the process of elimination in mind, let’s look at some more tests that you can do to identify where (and where not) your pool is leaking.

Water Level Leak Test

Let your pool continue to leak until the water level stabalises and stops receding. The level that the water drains to will be a huge indication of where the leak is located. Water levels don’t lie.

It is safe to temporarily lower the water level in your vinyl liner swimming pool so long as you leave between six inches to one foot of water covering the floor in the shallow end. Concrete pools can be drained as well but should not be left drained for long periods of time. By letting your pool water level drop you can often find the origin of the leak source.

If the water level goes down to the wall returns height and then seems to slow or stop there, you likely have a hole in the return line. Wherever the water line is when it stops receding, be sure to check the circumference of the pool for small holes, tears or punctures in the liner. If you are able to conduct this test on your swimming pool, whatever the result, the findings will help to further diagnose your water loss problem.

Protect Your Pool Pump

Please note that during this test it may be necessary to shut down your circulation system so as to not burn out your pool pump when the water level drops below the skimmer mouth.

If you have a mechanical installation that allows you to isolate the main drain and skimmer suction lines and close off the skimmer, you can continue to run your pool through this test. Never drop the water level in your pool lower than 6-12” of water covering the shallow end, and avoid prolonged periods where the water level is dropped this low, especially with older liners.


Water Level Leak Detection Results

The water level in your pool when it stops receding is a direct indication of the leak source. This information can be crucial in identifying the leak location. Choose the water level that matches the results from your water level leak detection test from the right hand menu.


Gaskets & Faceplates At Waterline

If the water level stops anywhere where it is in contact with a gasket, such as the skimmer mouth faceplate, or an in wall set of stairs, this location will need a specific dye test done to determine if a leak is present.
Additionally, you can select the appropriate screw driver, which is most commonly a Phillips driver, less commonly regarded as the “star” shaped one, and check that the screws at, above and below the waterline are snug. You certainly do not want to snap the head off of any screw, as this is just a thankless and aggravating repair to deal with. You simply are trying to identify if each screw is holding solid and not spinning loose or free in its hole. If you have a broken, loose or missing screw, you have definitely found at least one leak that needs to be repaired. Seldom will a pool remain watertight if a screw is broken, missing or damaged along a compression gasket and faceplate such as the skimmer, returns or stairs.


Below Skimmer But Above Returns

If the water level drops below the skimmer mouth anywhere down to 18" below the bottom of the skimmer mouth and then stops, you may still have a leak in your skimmer. Quite often you will have an equalizer line in your pool either independently in the wall, or underground connected to the main drain. This allows your skimmer to access water below the mouth of the skimmer; a prevention method to stop your pump from losing prime should the water level fall too low.

A crack in the skimmer itself, or in the pipe connected to the bottom of it would cause the water level to drop to this level and then stop. Skimmers are especially prone to migrating soil conditions, freeze and thaw conditions and contain underground piping that can often be older than the remainder of your pool plumbing. An equalizer from the bottom of the skimmer to the main drains would likely be overlooked during a renovation so it can be a common leak source. Worth noting also is that a water level in this range could also indicate a broken plumbing pipe underground. The water level in the pool would match the elevation at which the crack exists in the pipe outside the pool.


Water Level At Return Outlets

If the water level drops to the level of the return ports and stops the leak will likely be located in the return line. It could be in a gasket, in the pipe, or in the fitting itself, but the water level is pointing clearly to further investigation of the return line.

This is one of the most common swimming pool leak locations, and a water level indicator pointing towards the return lines would make likelihood of finding a leak in this location very high.


Water Level Drops Indefinitely

If the water level continues to drop right up until the point where you need to add water to maintain the 6-12” of water in the shallow end minimum, then you need to inspect the liner again for leaks. Use the opportunity while the pool is partially empty and inspect the lower wall and floor sections of the liner up close for any damage, rips, tears or separating seams.

The corners of the pool are a common location for holes in the liner, often caused by maintenance equipment such as vacuum heads and brushes. The deep end corners are even more susceptible to holes in the liner since the liner is stretched tighter in the corners there from the weight of the water in the deep end pulling downwards. These deep end corners are obviously harder to inspect than the shallow end ones, but warrant inspection all the same.


Leak Detection Dye Test

The dye test is a quick and easy test that can be completed by anyone. It takes a skilled eye to spot a small leak, however larger leaks can be witnessed by most anyone. Special dye can be purchased from pool supply stores in a syringe for easy application to the suspected leak area. As a quick and easy replacement for this dye you can use either red food coloring, or the red dropper liquid from old swimming pool water chemistry kits.

The dye is injected in the water in tiny amounts directly adjacent to suspected leak areas. If the water is relatively calm, the dye will float casually where you have squirted it. If a leak is present the dye will be pulled from its casual floating position down into the leak. Please note that to test a return gasket for example, you would slowly and carefully submerge your arm trying to disturb the water as little as possible and squirt the dye to within an inch of the suspected leak. If a leak is present the dye will gently float back and forth with the motion of the water, and you will see it begin to disappear into the leak. Although this is a good preliminary check that can be preformed by anyone, it is a low-tech precursor to far more reliable testing methods such as pressure testing and require a keen, often skilled eye to interpret test results accurately.


Common Pool Leak Locations

Certain swimming pool components are prone to failure more than others. This section will deal with the most frequently encountered swimming pool leaks and the associated symptoms that accompany them. From the previous leak detection tests we have covered you should be able to recognise some of these symptoms as they relate to your swimming pool leak.

Remember that each swimming pool is unique and therefore these common leak areas may not display all or any of these symptoms. This information should be used in conjunction with diagnostic testing methods to narrow down the possible locations for your swimming pool leak.


Holes In Vinyl Liners

A hole in the vinyl liner itself will have accompanying characteristics that go along with the obvious signs of water loss. If a pool is losing moderate amounts of water through the liner itself, you will often experience a situation where water accumulates underneath the liner in your pool causing the liner to float up off the floor of the pool slightly.

This is not necessarily a dramatic effect that will be immediately obvious. Close inspection of the floor will help to determine if there is excess water under the liner, specifically in the deep end of the pool. If this is the case it is very likely that you have a hole in your liner.

Consider All Relevant Information

If you suspect a hole in the liner of your pool you should also consider the relative angle and overall condition of the liner as a whole. If the liner is old, faded, cracked, ripped or of an unknown age you can expect that a hole in the liner might exist.

Be sure to check your maintenance equipment such as vacuum heads and brushes for any sharp protrusions, which might inadvertently cause a rip in the vinyl liner. Additionally all toys and clothing used in the pool should be such that is poses no risk to puncturing the liner.

Seeking a small hole in the vinyl liner can be difficult so identifying why the leak exists, or the instrument that caused the leak, can lead you to locate the hole in the liner much more readily.


Hydrostatic Relief Valve

Other than the obvious condition that the pool can drain indefinitely, the only other obvious sign of hydrostatic relief valve failure is occasionally you will see a cloud of murky water appear at the bottom of your pool. This cloud is the ground water from beneath your pool accessing the inside of your pool. In short bursts, this murky cloud of water should be considered normal as the valve relieves the water table pressure.

Constant cloud or frequent clouding even during relatively dry periods should be considered abnormal operation for the hydrostatic relief valve. It is a mechanical connection, meaning it relies on moving parts in order to operate, and it will wear out eventually and thereby requires periodic replacement as preventative maintenance. Each time you replace your liner, be sure to have this inexpensive item replaced as well and you should be fine.


Filter Head Gaskets

The condition where water escapes past the built in one-way valve in the filter head is a major source for unexplained water loss in in ground pool installations with a permanent discharge line attached to the filter. Many filter types can have this problem where a backpressure on the filter head will cause the internal gasket to shift and allow water to leak past the check valve in the filter head and drain out through the backwash line under normal pool filtering settings.

Many easy fixes are often witnessed for this condition, most commonly being a manual ball valve that prevents water from escaping into the backwash line. The downside to this easy fix is that the valve must be manually opened to backwash and manually closed afterwards.

The correct solution to this problem is to open the filter head (NOT while under pressure) and reset the gasket, which will be out of its obvious position. This condition occurs when the water being pushed through the backwash line creates a vacuum after the filter is put back to “filter” from “backwash”. Changing this dial setting closes off the backwash line with a watertight seal.
The water in the backwash line is still moving however, and if there is no air gap in the backwash line (if it is full of water), a temporary backpressure is created as the water continues its path through the pipe and away from the filter. Even a small backpressure is enough to pull the gasket out of position of many models of filter.

Worth noting in specific is the Tagelus make T-100 filter heads which where industry standard for many swimming pool constructions from 2003-2008 which have an excessive history of this problem. In addition to the manual resetting of the gasket, a correction of the problem must be taken as well to avoid backpressure from being created.

Primary Leak Symptoms

A leak in the filter can be elusive to diagnose. An easy check to see if your filter is leaking through the backwash line is to remove the filter sight glass when the pool is in normal filter mode. The sight glass on the filter is designed for you to view the water clarity that is being backwashed through the filter. When in regular filter mode no water should be able to access the sight glass.


Leaking & Cracked Skimmers

Should the skimmer be leaking, there are a few conditions which can appear in the regular operation of your pool system which may help to confirm that the skimmer is the origin of the problem. Cracks in the skimmer can be a common cause of water loss, often resulting from shifting soil conditions or improper winter maintenance.

Since water accumulates in the skimmer, it can freeze in cold conditions and cause tremendous outwards pressure that can crack the skimmer itself. Close visual inspection will help to determine if you have a crack in your skimmer. Should the leak be underground, often the point at which the suction line connects to the bottom of the skimmer, this leak will manifest itself as an increased difficulty in priming the pool pump on start up.

If your pump location is higher than the water level in the pool, this priming difficulty will become more apparent as the leak in the skimmer line worsens. If your pool pump is located lower than water level, your pump should be significantly easier to prime even if there is a small to moderate leak point in the skimmer line. In this common situation, an excess of bubbles or air present in the pump sight glass can indicate that the suction line is pulling air from somewhere.

Note that most swimming pool pumps have a small amount of air entrapped in the top of the sight glass during operation, so a leaking skimmer would increase the amount of air seen in the system. Leaking pump seals, winterizing plugs, gaskets and O-rings on the pump can also independently cause the condition of excess water in the pump sight glass.

Skimmer Hydrostatic Test

If you suspect that your skimmer may be cracked but are unable to visually identify the location, you can use a hydrostatic test to determine if the skimmer body remains structurally sound. To complete this test you will need to lower the water level of the pool below the mouth of the skimmer, as well as plug any open ports in the bottom of the skimmer with a suitable rubber expandable plug, or a threaded winterizing plug with silicon tape as a gasket on the threads.

Simply fill the skimmer to capacity, mark the exact water level with a pencil, and monitor any water loss over a period of time. If the water is escaping, it can only be doing so through the body itself as the bottom ports have been isolated from the plumbing system. A dye test will be able to show you exactly where the water is going. Beware that your plugs are not slowly leaking and giving you false readings with this test. If in doubt, replace the plugs again and repeat the test for accuracy in your findings.


Leaking Pool Return Lines

Leaking return lines are the most common cause of unexplained water loss in swimming pools as should always be scrutinized heavily when searching for an unexplained leak. Returns are installed in two stages with the initial stage being a two-piece flange that is mounted through a hole in the galvanized steel wall of the pool. This is the receiver portion of the return faceplate and gasket, which allows for the watertight seal over the vinyl liner in the finished product.

This return fitting itself will seldom be the cause of a leak due to cracking, and more often cause of leak due to improper return gasket installation or failure. The return line pipe is connected into the back of this return fitting via primer and glue for PVC pipe, and utilizing stainless steel clamps for the older polypropylene style pipe. This connection point to the back of the return point is the single most common point for swimming pool leaks.

Why Are Return Leaks So Common?

When a pool installer attaches the pipe to the swimming pool return, the pipe must elbow down immediately. If you do not turn the pipe ninety degrees downward directly out of the return fitting, over time the migrating soil conditions will cause a leverage point where the pipe meets the return fitting.

By turning the pipe downward you alleviate the potential leverage of this joint. Should the pipe exit the return fitting and go straight out horizontally a foot or two the end farthest from the pool return needs to only shift a half inch to one inch for the joint where the pipe meets the return to fail. I cannot stress how common this problem is which the vast majority of installers today even still making this common mistake.

Additional Return Line Symptoms

An immediate cause for concern is when you can see that the deck area of your swimming pool has been broken open and repaired by one of the return fittings, but not by another. In this situation the returns have already proved to be unreliable and it can be a matter of time before further failure is experienced.

Bubbles, large or small coming from the return ports of your pool is a clear indication into a leak in the plumbing system. The only exception to this is if you have an ozonator system installed on your pool, which will also cause small bubbles in the return ports as part of its routing operation.