Newbee here. Have had a kenmore water softener installed for about 5 years with no problems till 9 months ago. The brine discharges into a vent pipe to the stool. Slab house with about 50 feet of drain line before it tee's into another 4" line then out from house to street drain. The 4" pipe is clogged and no water will pass. Had stool removed and line snaked out 2 months ago and was fine till just now plugged up again. We only pee in this toilet so wifes toilet paper is only solid going into it. The washing machine dumps into same drain about 15' from stool. Could the discharged water be setting in the drain pipe and hardening? When it was snaked out we got chunks of white material out of it. No ideas what it was. My question is could the water softener be causing buildup in the pipe? Thank You