7. What does a reverse osmosis system look like and where is it installed?

Most RO systems are compact units installed under your sink. (In some cases, they can also be installed on the countertop). A typical system is comprised of one or more pre-filters, a reverse osmosis module, a post-filter, and a pressurized holding tank (see diagram below). The pre-filters trap sediment, chlorine, and other contaminants before allowing water to pass into the reverse osmosis module. The RO module, containing the RO membrane, further isolates a range of contaminants before allowing treated water through the post-filter. The treated water received a final “polishing” as it flows through the post-filter and into a holding tank connected to a tap on the kitchen sink. The waste water rejected by the RO is sent down another line into the drain.