Waste Line to Sewer


Jul 16, 2019
Houston, Texas
I have a 15,000 gallon pool with a Hayward swim clear cartridge filter. I have always been under the impression I could not vacuum to waste because there was no waste function on the filter or otherwise in the plumbing.

Yesterday, I was looking at the plumbing near the filter. And I think there is a waste pipe that can be triggered with a three way valve.

Description. There is one pvc pipe coming from the back of the pump. Before it goes into the filter, there is a three way valve. Inlet from the pump and two options. One goes into the cartridge filter. The valve is set to permit water flow in this direction so the system can clean and send it back into the pool through jets or waterfall.

I noticed the other pipe would bypass the cartridge filter altogether. It goes 3 inches out, takes a 90 degree turn and goes directly into the ground. If I moved the valve handle, all water out of pump would bypass the filter and go through this pipe.
Now, the problem is I don’t where this pipe goes. It doesn’t appear to connect to the return plumbing. So it doesn’t appear to be simply a cartridge bypass. Is it possible that the pipe connects directly into my city plumbing? And it would merely send all water released from the pump to waste? I guess I could just try it and see what happens, but I’d like some confirmation from someone who knows more than me before I do it.
Thanks in advance.

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Some cartridge pool owners are lucky enough to where the builder installed a 3-way between the filter and pump which serves the same purpose as a WASTE function. If you have that - great! As to where it goes, your guess is as good as ours, but if it goes to city sewer, I don't see the problem unless your city or HOA has some sort of issues with it. Codes vary from place to place.

You can always post some pics too.


Gold Supporter
May 20, 2020
Katy TX
Pool Size
Liquid Chlorine
I agree with Texas Splash, it probably is a waste line to the underground sewer system. The rules in Houston area vary with regard to putting waste water through your sewer system or directly to the street. My neighbor goes to the street while mine goes to the sewer line. Pools built at different times. My line comes back up in my front garden, makes a 180 deg bend and goes into the sewer line. For some reason I can physically see the water entering the sewer line (its not a physical connection, just the pipe outlet above the inlet of the sewer line, not sure why but that was most likely the code back in 2002 when it was built).. suggest you put it to waste and pump, then go search if you see or hear water in a line. Also monitor the pool water height to see if it is truly draining.
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