Swimming Pool Blog
by Rob Cox, October 03, 2012
The Most Common Pool Leak
My cousin Joe sent me an email with the subject line: The Pool is Leaking. Knowing his pool the way I do, I immediately emailed him back a response.
"Lay on the deck and lean over to look inside the skimmer. Look for any cracks at the point where the plastic skimmer meets the white plaster. If you see any debris sucked into these cracks or voids, a pool putty repair is indicated."
I love trying to sound like a doctor! Joe found the cracks and the debris, cleaned it up a bit and made a pool putty repair (described below).
Pool Skimmer Leak Problem: Inground gunite pools can develop a crack where the plastic skimmer meets the concrete pool wall.
There are two ways to install a pool skimmer when a gunite pool is built. The first method is to place the skimmer into the steel frame that makes up the pool wall, and shoot gunite (or shotcrete) around the frame, encapsulating the skimmer in a dense and monolithic quantity of concrete.
The second, more common method is to leave a notch in the wall where the skimmer will go. After the gunite is done, the builder will "peg" the skimmer to the pool wall, by drilling 2-3 holes into the back of the pool wall, on each side of the skimmer.
Rebar is bent from one side of the skimmer around to the other, and forms are constructed around the skimmer. Hydraulic cement is poured around the skimmer, rebar and back of the pool wall, to hold the skimmer to the backside of the pool wall.
Problem with the second method is that ground movement or expansion and contraction from temperature swings will eventually cause this "Cold Joint" between the pool and skimmer to separate. The movement will allow small cracks to develop at the point where the plastic skimmer body meets the concrete pool wall.
Pool Skimmer Leak Inspection: Lay on the deck and look upside down into the skimmer, to locate the area where the plastic skimmer meets the concrete pool, usually at the point where the tile ends. This area is usually parged in with plaster.
Take note of any small cracks or voids - and look for areas where small bits of debris have been sucked into these cracks or voids. You will look on 3 sides; the bottom, and the left and right sides. The problem area may not be underwater, but may be at or above the water level.
If you want to verify the existance of a leak, you can dye test the suspected cracks with food coloring, or our pool leak dye syringes. To do this, shut the pump off and allow the water to become still. Lay on the deck again, with your arms in the water. Clean any debris from the area with your hand, and then slowly squeeze out a bit of dye near the suspect area. If it is leaking you will quickly see the dye being pulled towards and sucked out of the pool.
Pool Skimmer Leak Repair: After the leak is found, spend a few minutes with a flat head screwdriver, cleaning up any loose debris, and opening up the crack a little wider. If you notice previous pool putty repair jobs, it may be best to remove the old putty with your screwdriver, to create a larger, clean joint to push in the new pool putty.
Then, mix equal parts of an underwater pool putty, such as Epoxy-Bond or Leakmaster, together with a bit of water, until the color becomes uniform. Roll sections of the mixed putty in your hands, to make a "snake" of putty, 3-4 inches long. Push your putty snake into the void or crack and press firmly. Smooth out the edges with your fingers and be sure it doesn't interfere with the skimmer weir operation. (that flapper door thingy)
Your leak will be immediately repaired. The putty will harden and will hold fast, perhaps for several years, until more movement is enough that your repair will need to be redone. Why not just replace the skimmer? You might ask. That, my dear reader, is a topic for another day. Pool Putty is a simple 5 minute fix. Replacing a skimmer encased in concrete is a real undertaking!