Installation and Service Manual
– Under-the-Counter Point of Use 5 Stage Reverse Osmosis System
Copyright © 2022 Applied Membranes, Inc.
All Rights Reserved.
Page 19
RO BASICS
This section provides basic concepts on how an RO system works, how it performs in relation to your house’s
water condition. We hope this information helps keep your RO system running at top performance for years to
come.
Basic Terms
GPD = Gallons Per Day (flow rate)
PSI = Pounds per Square Inch (pressure)
TDS = Total Dissolved Solids (contaminants)
PPM = Parts Per Million (unit used to measure TDS level)
TDS Meter = A digital meter for measuring the TDS level in the water
Flow Diagram for 5-Stage or 6-Stage RO System:
The diagram below shows how water flows through the RO system from Feed point to Output point.
Input water starts from Main Water Supply, going through stages 1, 2, 3 pre-filters, then enters the stage-4
membrane. Product (filtered) water from the membrane feeds the storage tank; the “brine water” from the
membrane drains out through the drain line. Product water from the tank passes through stage-5 filter (then
optional stage-6 filter) before reaching the dispensing faucet.