Hello all, I just installed a new Ro
unit under my sink..... It was the cheapest one I could find that still did everything I wanted it to so the instructions are a little under par! I was hoping someone could answer a question for me..... There is a line going to the faucet, and a line attached to the drain of the sink..... The line going to the drain has a ball valve on it...... Does this unit operate with the drain line valve open or shut?!?! Or is that just for purging the system or flushing the filters?!?! Any help would be greatly appreciated!