Reverse Osmosis – Part Three Of Three

Now that we know how to create an RO process in a two-compartment tank, we need to know how to build an actual RO machine that will give us a continuous flow of purified water. We need five ingredients to convert our RO tank to become a purified water-producing machine capable of continuous flow;

  1. A fresh tap water feed line
  2. A pump to overcome the forward flow of osmosis and drive production at a higher flow rate than just line pressure
  3. A product collection outlet to collect the purified water we are about to make
  4. A waste/reject line to allow water from the RO machine to go to drain
  5. A reject valve to adjust the ratio of purified RO water produced to the amount we send down the drain

These ingredients are shown in the drawing provided

It is important to note that no RO machine can be 100% efficient. The better ones can achieve a production efficiency ratio of 75 – 80%. This ratio is commonly called the recovery rate. A machine that has a recover rate of 65% for instance will produce 65 gallons of purified RO water while sending 35 gallons of concentrated water to the drain.

Remember, an RO system does not destroy contaminants, but rather merely concentrates them and forces water into the purified line. The reason that and RO system cannot ever be 100% efficient is because there must be water sent to drain to transport all the concentrated contaminants away from the RO membrane. Otherwise the contaminants would build up and plug the RO membrane.