Will the siphonic flush effect still function if a port is introduced behind the water seal on the outlet side?

Not sure exactly what you are asking. Realize that there is a "port" called the vent, on the outlet side. In fact, there may be many added drains to the main line. Exactly what is your proposal.

Thank you for your response. If an inlet port was introduced behind highest point of the trap, would it adversely effect the flow of water and waste into the sewer drain?

"port is introduced behind the water seal " can you better tell us what this means, and by seal do you mean the wax ring?

Hi Daniel

We are glad to help, but we need to know what you are trying to do. As plumbers we are concerned about backflow issues, cross contamination, and keeping people healthy, so you'll need to clearly state what you are trying to do, how you are trying to do it and what you expect as an result, OK?

Back to you...

Mark

I have a toilet in a very small area. I want to install a small basin that would sit on top of or adjacent to the toilet. Can the basin drain directly behind the water seal if an inlet is introduced and will the toilet still flush?

That is impractical, against code and as waste water would flow from the toilet, pressure would force the waste back through the sink drain.

Thank you

Hi Daniel

They make toilets with integral basin.. See image. There are many options on this, but probably not cheap!

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