I am installing a kenmore water softner and need to hook up the drain connection and overflow. Next to the softner is a 2" pvc pipe coming from my kitchen sink. This pipe goes directly into the house sewer connection. Is it OK to hook the softner drain and overflow directly into the pipe coming frim the kitchen sink. I am concerned about sewer gases, etc. If is not OK do you have any suggestions?

Pipe it separately to the outside.

I don't know what code says, likely I am grandfathered. Better find out for a new installation. My water softener is next to the washer and drains into its stand pipe and then to the septic tank. It has been that way since the house was built in 1970, and I never saw a problem. I do have the overflow piped separately to an outside area where I don't try to grow anything. If the softener is in the basement, running the over flow outside will be tough.

The washer standpipe provides the trap and vacuum break needed between the water softener and the sewer.