Carbon Filter + Softener Drain Review

[mario389]

Hi All,

I'm hoping to get some confirmation (or flack) for my whole house carbon w/backwash + water softener drain plan.

Details:
- Both Fleck 5600SXT valves
- No floor drain
- Sewer is about 4 ft up and let's say max of 10 ft 'over' from the discharge on the Fleck valves
- Builder provided 3" > 2" wye with 1 ft cap for a future grinder pump for roughed in basement bath. The pit is directly below the wye.
- We do plan on adding a full bath in the basement (Shower/tub, sink, toilet)

Picture of proposed drain location and plan: http://i.imgur.com/1AEwYDc.jpg (Sorry, I tried and failed at a Google SketchUp).

My plan: Cut the cap, then add a 90 away from the back wall/rim joist. 4" of 2" straight > wye + trap > 4" of 2" straight > wye + trap > 4" of 2" straight > cap. Once I add the bath/grinder pit, I will cut the cap and add another wye/trap.

Questions:
- Am I in the ballpark here? Is there a better approach? Following code is important to me
- Is this 2" drain enough to support these 3 items?
- Are 2 traps really necessary? Any way to get both the softener and the filter in the same trap? I'm thinking sink/dishwasher.
- Is flex line from the Fleck discharge to trap ok, or should I use PVC? I've seen mixed opinions on this since I'm going overhead.
- How far 'down' the wye should I cut?

Thank you!

 

[Reach4]

Drains can go up to the ceiling and beyond.

http://www.tru-gap.com/Details.html can combine 3 drains into 2 inch pipe through an air gap.

It seem to me that you could wye the two drain lines together before an air gap, but I am not sure that would be permitted. It should work fine if you don't overlap the regens.