Back in the old days, leak detection hinged on a good eye and a syringe of dye.
And while modern electronic equipment can be great for locating
leaking pipes underground, precise observation and solid instincts
still hold the keys to effective detection.
In fact, developing a reliable, thorough process for finding leaks
comes with experience, and plenty of trial and error. But
it’s never too early — or too late — to begin
mapping out such a process.
When dealing with leak detection, it’s important to check a
variety of factors. And understand that even when a leak is
located, the process doesn’t stop there, because quite often
more than one problem exits.
Scope out the area
Begin by observing the equipment while it is running. Are there any
equipment leaks? Then check the waste line, and see whether it is
equipped for water loss with the system running.
Next, turn the system off, and slowly walk around the pool,
checking to see if any water is leaking through the wall.
Make a mental note of any unusual observations, such as previous
patches, discoloring in the finish, or leaves stuck in the wall.
Scan the deck for cracks that may continue through the coping and
travel further through the tile and/or down the walls.
Are there any signs on the deck that indicate it has been opened
for an underground repair in the past?
Ask questions of the homeowner, or whoever else is taking care of
the pool. What observations have they made regarding water loss?
How long has the pool been leaking? How much water does it lose in
a 24-hour period? Does it lose more with the pump on or off?
These initial observations and questions will provide valuable
information for the next steps of the investigation.
Begin the examination
Everything up to this point has been mental. Now it’s time to
utilize the professional skills.
If you have access to an electronic listening device with a
hydrophone, this is the time to use it. Place the hydrophone by the
returns, the vacuum port and the main drain pots, and in the
The turbulence created by certain leaks can be heard. If a
high-pitched noise — similar to a jet flying by — is
evident, it may indicate a problem in this area. (But remember to
look up, as there may actually be an airplane overhead.)
Realize also that 90 percent of leaks occur where two different
materials meet. Remove all eyeballs, vacuum port covers, main drain
covers, etc. and dye test anything that looks unusual. Remember:
“If it catches your eye, it may pull dye.”
Examine hard-to-see spaces by using a mirror and flashlight. If any
leaks are apparent at this point, clean the area around the leak
with a steel brush and prepare some two-part epoxy.
Repairs with epoxy
It’s important to check the epoxy’s packaging to ensure
it’s a type that will harden underwater. Any swimming pool
supply store should have this kind of epoxy on hand. It’s
typically available in both white and black, so for aesthetic
purposes, it may be helpful to mix equal parts of each color to
create a grey substance that will be invisible on the pool’s
The epoxy package will contain “Part A,” which is the
resin, and “Part B,” which is the hardening agent. Cut
two portions equally of A and B, and combine them by rolling the
mixture into a ball until its texture and color are consistent
throughout (gloves may be helpful for this step).
Apply the epoxy to the crack or around a fitting, smoothing it by
applying fingertip pressure. If the leak is coming from behind the
light niche, be sure to mix enough epoxy to plug up any holes at
the back of the light and around the cord.
An alternate product is butyl tape, which is hand moldable, sticky
and very flexible, and may be ideal for sealing a leaky light
conduit around the cord.
The homeowner may have indicated that more water seems to be lost
with the pump on, which means a few other checks may still be
Pressurize all lines to about 20 psi. Make sure that when plugging
the lines, the plugs don’t cover up the problem. If the
return line or pressure line fails to hold pressure, it’ll be
necessary to use electronic devices to identify the exact location
of the break.
A pressure rig should be capable of injecting water and air into
the line separately. Inject water first to flood the area around
the leak, creating a pool of water. When just starting to use the
equipment, it is good practice at this point to drill a small hole
through the deck or ground and send a rod down to make sure there
is water present.
Next, inject air and listen through the deck using the headphones
and electronics — try to pick out the bubbling sound that
indicates air is escaping into the pool of water around the pipe.
When the loudest sound is heard, mark the spot.
If water appears, it may be necessary to replace that section of pipe.
After the broken or cracked underground pipe is located using the
electronic equipment, the area must be excavated, making a hole
large enough to cut out the section of pipe. A coupling and PVC
glue will be needed to repair the pipe.
A pressure test of the pipes is advisable before replacing the dirt and the concrete.
Only a licensed pool contractor or plumber should perform these
repairs — especially if the pipe is located underground or
sealed within concrete. Attempting such work without the proper
training may result in serious damage to the deck or piping.
While these are only the basics of locating leaks in swimming
pools, a process such as this can provide a foundation for success.
To become an expert, one needs patience, determination, knowledge
and the proper tools. The best tool, however, is always the one
between your ears.