A swimming pool’s main drain is not really a drain because it is not used to drain the water from the pool. It is an outlet that houses a pipe that connects to the pump, that sucks water via the skimmer, then via the filter, then via the heater (for pools with one), and then back to the facility through multiple inlets.
The latest pools come with two main drains positioned at the deepest point of the pool. However, the small models might have a single drain.
Testing If the Main Drain is Working
You can test if the drain is working correctly by placing a tennis ball to the skimmer hole. The ball should be large enough to cover the hole and not get sucked into the system.
You can easily see if the ball gets sucked to the skimmer hole, and that is enough proof that the main drain is working correctly.
However, some pools have excessive concrete that might have covered the entire suction side and almost shut it off. Using a tennis ball can make the water and ball fuzz around and damage your pool.
Here, you can do the following test:
- Add some dirt around/on the main drain to see if it gets sucked right away (you can vacuum it after the test)
- Move to the edge of your pool and watch the main drain keenly while holding the tennis ball in position at the skimmer (feel the suction power).
- Get someone to turn the pump on for about 10 seconds and see how it responds.
Clogged Main Drain
If you do not skim your pool regularly to remove debris floating around, they can quickly get to the bottom and clog the main drain. These can be leaves, sticks, hair, pollen, and other materials.
It is easy to put them in one place and remove them from your pool before they block the drain.
Cleaning the Main Drain
Once you have skimmed the top and removed all the debris, you can now remove the drain plugs. Then leave the drain to do the rest.
After the water is drained, take out the drain cover and release any stuff that might be trapped in the drain using a plunger. You can now have the confidence that your main drain is clear and working correctly.
You should clean your pool regularly to ensure that the main drain continues to function correctly. I have listed some few tests that you can conduct to know if your system is working correctly.