Baumann Aquatics Logo

A question and answer conversation to help determine if and where a pool is leaking.


Q I think my pool is leaking.  What should I do next?

A:  First thing to do, determine if the pool is indeed leaking.  This can be easily determined with a standard bucket test.  Simply place a solid plastic bucket (preferably, the same color as the plaster of your pool) in the top or second step of your pool – wherever the top of the bucket is just above the pool waterline.  Fill it with pool water (not tap water) to the current level of the pool waterline - and, to weigh the bucket down, use a stone or other heavy nonabsorbent object that is close to the same color as the bucket or pool finish.  (The bucket and bucket weights should match the pool finish color as closely as possible because differing colors have an impact the rate of natural evaporation.)  Next, mark the water levels inside and outside of the bucket and then monitor and record the water levels for the next couple of days.  As both the bucket and the pool will be subject to the same rate of evaporation and weather conditions, this will be a way to measure in inches how much the pool is losing water relative to a control unit.  Do this test first with the pool filter equipment off (static water loss test) and secondly with the pool pumps and filter system running (dynamic water loss test).  This test works best when there is little or no user activity in the pool.  Time frames for the test will differ, depending on rate of loss and weather conditions, but it is normal for each test to take two or more days to deliver visible results.

Q:  The static water bucket test (pumps were turned off) showed that the pool lost two inches of water more than the level of water in the bucket - in one day.  What does this mean?

A:  First – and most importantly – this means that you have a leak problem that will not go away until it is corrected.  (Some leaks can be worked around to minimize the water loss. Not in this case.)  Second, this means you must determine where the pool is leaking – in the pool shell, the plaster finish, the lights, around the skimmers, in the tile, or in the plumbing.  It is best to not assume anything, no matter how seemingly obvious a correlation may appear to you. 

The first place most pool technicians look is the pool light or lights.  There is an electric cord seal in the metal housing (light can) in the wall of the pool where the underwater light bulb is seated.  This seal encases the electric cord at the opening of the conduit.  This opening is plugged using a variety of sealants (epoxy, silicone, etc.) and if they deteriorate (due to aging, water chemicals or other factors) the water loss through the conduit can be quite pronounced. 

The second place most pool technicians check is around the skimmer.  The skimmer mouth is a place where cracks in the grout or at the interface of the plaster seal can cause major water loss. 

The plaster seals around any drain fixtures, in the floor or in any vertical surface, should be carefully examined.  The plaster surfaces around any pool (or spa, or any other water feature) return line opening should also be subject to close examination.  These openings are usually the end points of pipes that were cut off just beyond the edge of the gunite shell and then plastered around.  Sometimes the plaster around these pipes recedes and plaster holes occur directly next to the visible pipe surface.

The entire pool plaster finish should be examined underwater for any obvious cracks or signs of serious deterioration.  Finally, all tile near or below water level should be checked for cracks or holes.

Q:  How do I check for water loss at all of these places?

A:  This is not easy, if it is done thoroughly and properly.  There are a variety of dye products on the market that you release near any suspect area and then watch closely (with as little movement as possible) to see if it disappears into an opening in the pool plaster.  (The old standard observation tool has always been phenol red from any pool test kit.)  You will need a diving mask to observe the dye underwater and, in some cases, you may need a wet suit and a tank to stay down long enough to make an observation.  Take your time, check everything you see that may pose a potential leak problem and once you have determined which places are losing water, correct any and all of them with the sealant best suited to your plaster, tile or plastic fixture situation.

Q:  I am confident that the plaster, lights, tile, skimmer and return line openings in my pool do not leak.  I then did a bucket test with the filter running and the pool water dropped 2” relative to the water in the bucket - in one day.  What do I need to check next? 

A:  Short answer – all of the plumbing.  You next need to plug all of the plumbing lines at the pool.  Most pipe openings in the wall or floor of the pool can be plugged using rubber expansion plugs.  Skimmer openings and some drain openings are threaded and will require threaded clean-out plugs with Teflon tape and silicone wraps around the threads.  The drain openings that are not threaded will require an expansion plug (in cases where the opening is too large for an expansion plug, ball plugs should be tried).  Pool cleaner lines are usually best plugged with a 1½” threaded plug with a rubber O-ring.  Once all of the plumbing lines are the plugged, the bucket test can be used to determine what kind of water loss you have (with the plumbing lines completely sealed and no longer a possible source of water loss).

Q:  Using the bucket test, I believe that the leaking must be in the plumbing as all the possible places of leakage in the pool have been dye tested and are good – and once the plumbing lines are plugged, all signs of water loss stop.  What do I do now?

A:  A thorough pressure test should be performed on all of the plumbing.  Easier said than done.  First, check all of the expansion plugs to make sure they are tightly seated.  If you are using rubber expansion plugs on 1½” or 2” pipe you probably should not try to pressure test the lines above 15 psi as the plugs will tend to blow out.  Expansion plugs for 1” lines or smaller will usually hold at high pressure – 20 psi or greater. 

When pressure testing the plumbing, you are actually usually testing two plumbing components:  The plumbing you see (the filter system) and the plumbing you cannot see (the underground pipes and the lines in and under the pool shell).

Now comes the hard part – making sure the filter system does not lose pressure while methodically testing all of the underground lines to determine which, if any, might be losing pressure.  Describing the process necessary to accomplish this would fill a lengthy instruction manual and is too involved to detail here.  Simply put, though, no pressure test will be definitive if the filter system contains any plugs, gaskets, O-rings, valves, pumps, filters or water conditioning components that leak.  If the filter system being tested is the rare one that shows no sign of leaking under pressure, you should be able to use the water flow valves at the inlet and outlet lines to determine which lines show signs of pressure loss.  If this test is done thoroughly, this will take a minimum of two days, and usually more.  

Q:  I cannot get the filter system to hold 15 psi.  How do I test the pipes?  OR:  I got the filter system to hold 15 psi and tested the pipes and found one (or more) not holding pressure.  What do I do now?

A:  The answer is the same for both questions.  Find a company that is experienced at leak detection and plumbing repair.  Locating underground breaks in lines can be an involved and difficult task.  Beware of companies that just fill plumbing lines with water and start digging around looking for leaks or, worse, assume a leak is in a certain spot, with no tangible evidence, and start digging or jack-hammering out the deck trying to chase down phantom leaks. 

Baumann Aquatics has over 20 years’ experience using geophones to listen for underground disturbances.  In addition, our 29 years of experience plumbing residential swimming pools & spas and building pool filters systems enables us to methodically evaluate all of the plumbing and perform all repairs necessary with as little disruption to the pool site as possible. 

Please contact us for all of your plumbing repair and renovation needs!