Water softener drain air gap or check valve?

Hello

I just had a water softener installed. It was installed directly to my sewer line (municipal sewer system) via pvc pipe with a check valve (metal type), and then to a trap then to sewer line. The softener is about 30 feet or so away from where it hooks into the sewer.

Is this sufficient to prevent potential cross connection problem, or should it definitely be an air gap type installation? If so, I was thinking of connecting to the pvc drain pipe and drilling through the floor (crawlspace) and using one of these air gaps that fit on top of your washing machine drain


There isnt a problem with connecting the existing pvc pipe with the flexible hose type is there?

Thanks for any advice you can give

The softener should have an air-gap between the discharge and the sewer system/P-Trap.
Discharge line material should not matter

I have never seen that type but it looks O.K. from the drawing.