Water Softener & Filter Backwash Drain into Clean-out

[tallen84]

I am installing a water softener and backwashing carbon filter on the outside of my house (inside a small shed). The nearest drain access is a drain clean-out about 15ft away that I would like to tie into for the backwash and salt brine.

I live in Houston, TX so while freezing isn't a regular occurrence I am trying to keep it reasonably safe from the occasional freeze and run the drain line underground. (See attached sketch). My questions:

1) Is this the best way to do it?
2) Will there be any issue running underground and popping back up as long as the clean-out is lower than the air gap fitting?
3) Do I need a separate P-trap above ground where I enter the clean-out or will the pipe underground service as one large P trap?
4) What size should I use for this drain line? Is 1" sufficient or do I need to go larger?

 

[Valveman]

Moving to the softener forum. You should get more help there.

 

[Sponsor]

 

[Reach4]

2. The popping up means that it could freeze. A proper block of EPS foam could protect that from freezing. You could leave that in place, or could just put it there when there are freeze warnings. Maybe there is some prohibition about having a low spot in the drain line. I am unclear on that. So my comments are based on logic and not on code.

3. I would put the p-trap in the shed. It needs a vent, and since you are in Houston under UPC, you will need a thru-the-roof vent.


4. 3/4 would be sufficient, so 1 inch would be more than sufficient. If you could run PEX, then the piping is unlikely to be damaged by a freeze. But a freeze-shut would cause water to spew from your air gap.

 

[tallen84]

Thank you for the reply.

I think the drain line with moving water is unlikely to freeze due to the short duration of our freezes and the infrequent regeneration cycles with mostly salt water, but the P trap holding still water makes me think it’s likely to freeze and crack.

The idea of putting the P trap in the shed is possible but like you said I think I would then need a vent (which I was trying to avoid due to cosmetic reasons) or the trap would siphon out.

I came across a waterless trap called a HepvO, do you think this would work? Seems something like this may solve the need without a freeze concern.

 

[Reach4]

I came across a waterless trap called a HepvO, do you think this would work? Seems something like this may solve the need without a freeze concern.

HepvO 1-1/2 Waterless Trap

No siphonage, no noise, no smells! Dry sealing valve prevents the escape of odors from your waste system into your RV and eliminates the need for check vents.

www.dyersonline.com

It does have a UPC number, so should be OK... I had never heard of it.

The purpose of the trap is to keep the sewer smell out of your shed. Your thought that the big dip down would serve as a trap made sense, and maybe you could just go that route until somebody starts going thru your softener shed looking for UPC violations. Unlikely.

A house inspector may just assume that pipe was going to a "dry well".