Hi everyone. I recently purchased a water softener and would like to plum the WS drain to my existing 3" drain pipe that is mounted inside the joist horizontally. I have seen similar water soften drain plumbing that uses a San-Tee, P-trap, 1 1/2 stack pipe and a air gap device for water softeners with a barb fitting for the drain hose.

Here is the question..
In the picture below of my desired location of the WS drain, I'm not sure if I will have enough height in my stack pipe for the water to flow correctly out of the p-trap. As you can see in the picture I only have around 5" or so before I hit the floor board. Would this be enough? or maybe another setup is needed?..


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a few issues...
a 3 x 1 1/2 "Y" not a san tee is what you need. you can not put a san tee into a horizontal drain.
next, you need to vent the trap to avoid having it syphoned by water flushing thru the 3 inch pipe.
an AAV may act as a vent for you (if allowed in your area) but there may not be enough height to fit it.

The water from the softener SHOULD drain INTO the pipe, but, under certain conditions, the water IN THE PIPE may also overflow the "P" trap you install. IOW, it is a bad location to do what you want to do.

Thanks for the comments.

The picture below is my neighbors Water Softeners drain setup which was installed by Culligan.

I see the Wye pipe, P-trap and the stackpipe.

On top of the stack pipe is a air gap device for the water softener drain.

A friend of mine has the same setup that was done by Culligan as well.

Since the Wye isn't coming from the top of the pipe, is this prone to backflow?.





Edited 2 times.

The sanitary tee should be a wye and 45 or a combo and the vent should be below the trap but it will be clear water.

show this picture to the local plumbing inspector. he/she might like to know what "hack" work culligan installers are doing..
but, if you want to hire a company that does this kind of work or DIY replicating this installation , go for it..
no plumber here or anywhere else is going to tell you this satisfies code or that it won't be trouble a few years from now..

When I saw both installs and how the wye was on the side and not tilting up, I was surprised.

On my first post and pic, the pipe is coming from the ceiling and just started its slope. I followed the pipe down to an area where the pitch is 6 1/2" (top of pipe to ceiling) instead of 5 or so inches. This gives me more room for a stand pipe.

Could I route the hose to this location (30' from softener) with water pressure around 55psi?

Also, for the air gap. Suppose I don't use a air gap device like the one I previously posted. Instead place the drain hose on a 90 degree barb and have the barb drain into the open stand pipe with 1" clearance (air gap). This will give me room to position the wye outlet slightly to the top instead of to the side like Culligan did.

Please tell me you are not on a septic system.