—Leaks and diagnostics
A leak at the skimmer or a return
Skimmers and returns are where the pipework meets the shell, and the seal around them is a common place for a pool to lose water.
The skimmer and the return fittings are the points where the pool pipework passes through the shell, and the seal around each one is a common place for a pool to lose water. A leak there often shows as water loss that changes with the pump, or damp ground near the fitting.
Diagnostic guides describe what an owner can observe safely. They do not locate a fault; testing on site does that.
The source is confirmed before anything is opened. Whether the water level drops faster with the pump running or off, and whether the loss tracks a particular fitting, point the diagnosis at the skimmer seal or a return before the surround is disturbed.
01Summary
What matters most here
Where pipe meets shell
Skimmers and returns are the through-wall points where seals fail first.
Loss that changes with the pump
A change between pump on and off points at the pipework or a fitting.
Confirm before opening
The fitting is identified before the surround is disturbed.
02Detail
How the source is found
The skimmer seal
The seal between the skimmer body and the shell, checked for movement and water loss.
The return fittings
Each return and its pipe connection, checked in turn.
The test
The loss is measured with the pump on and off to separate the fitting from the pipe.
03Before you start
Before calling
Note the water level
Whether the loss stops at a particular level, which points at the fitting.
Compare pump on and off
Whether the loss changes when the pump runs.
Look for damp ground
Wet ground beside the pool near a skimmer or return.
—In practice
How to use this
Measure the water loss with the pump on and off, and note the level at which it stops, because those two observations separate the fitting from the pipe. Look for damp ground beside the pool near a skimmer or return. Confirm the source before the surround is disturbed.
Mistakes worth avoiding
- Opening the surround on a guess
- Disturbing the skimmer or return surround before the source is confirmed hides the evidence. Confirm first.
- Ignoring the pump on-off difference
- Whether the loss changes with the pump running points at the pipe or the fitting. Skipping that check wastes the visit.
04FAQ
Common questions about this
- Why do skimmers leak?
- The seal between the skimmer body and the shell can fail or move, and the fitting is where the pipe passes through. It is a common source of a slow pool leak.
- How do I know if it is the skimmer or the pipe?
- The water loss is measured with the pump on and off, and the level at which the loss stops is noted. Those two observations separate the fitting from the pipe.
- Can a return leak be fixed without draining?
- Often, because the fitting is reached from the pool side. The seal or the fitting is repaired in place, depending on what is found.
05Read next
More pool guides on this
- Testing a pool shell after renovationAnother way faults and leaks are traced.
- How pool leak detection worksAnother way faults and leaks are traced.
- Planning a villa poolAnother stage of planning and building a pool.
- The stages of building a poolAnother stage of planning and building a pool.
Filed under technical diagnostics & leak detection. Every pool guide is listed on the pool guides page.
—NEXT
Losing water near a fitting?
Tell us where the level drops to and whether it changes with the pump. We will confirm the source.