Hey inspectors!
Preparing for a DIY install on a water softener here in Phoenix Arizona. I need to replace a broken shut-off valve anyways, now would be a great time to include a softener. The unit is located in the garage, however I have no drain available for discharge. Typically water softeners will cycle about 40-60 gallons of brine once-a-week (or more), as part of their regeneration cycle.
In my area, it’s not uncommon to run these discharge hoses into the ceiling to drain them elsewhere (Laundry room basin, washing machine drain, etc) My Laundry room is out of reach for this project.
My question is this, I have a bathroom about 25ft away. I was thinking of running the hose into the ceiling, and using the vent pipe for that bathroom. The drain hose has full household pressure, so it’s not gravity sensitive. Of course, I’d include a P-Trap, check valve, and Air-Gap. I couldn’t find any negative or positive comments for an approach like this.
Any thoughts. Otherwise, I’m going to be forced to route it into my neighbors pool. 
Thank-you for your time!