Rainsoft 2008 Silver Series Installation Manuel

as you are looking at the front of the unit, there are two main lines straight out the back. , water in on the right, out on the left. Actually could be arrows pointing in and out on the valve/bypass, if you look closely.
just behind the front case the brine tank attaches to the right front side of the valve via 3/8" tube/ brass nut , the drain line attaches to the flow control on the left front of the valve, usually through an elbow.