I want to install/repair a utility sink in my basement but the main waste line is mounted to the wall about 4 feet off the floor. What types of elbows, back flow valve and positioning, venting, etc. do I need.
The current set up has the utility sink as the last item entering the main waste line. There is a back flow preventer that is set horizontally immediately after the pump (no elbows) and is not working correctly because every so often the pump refills with water and it sends it up the pipe to the main only to have a small amount return and it starts all over again.

Please advise on the correct items and installation needed to correct this.
Thank you,
Dan

You will get a little backwash from the check valve back through the pump into the trap when the pump shuts down. Is this your complaint? Tom