These pumps MUST be oriented properly. There are arrows pointing up, and labels for each inlet/outlet.
1 - The word Permeate is the word used in the industry for the good, drinking water that comes from your RO system.
2 - The word Brine is the word used in the industry for the waste water that comes from your RO system.
3 - The line that comes from your RO membrane and goes to your pressurized holding tank will go to the inlet labeled permeate.
4 - The outlet labeled permeate will go to your pressurized holding tank.
5 - The line that comes from your RO membrane and goes to your waste will now go to your brine inlet on the permeate pump.
6 - The line labeled brine out is your new waste line and goes to your drain.
Please note, the permeate pump needs to run on an RO/DI system that has a pressurized holding tank for it to operate properly.
Hope this helps.
Russ