RO Unit Components: Basic Assembly
Randal Bogarth March 1, 2003

Hi All! Due to an overwhelming demand, myself and the Simply Discus Team present the first in a series of RO unit education threads. In this thread I will walk you through some of the basic components that I use when assembling an RO unit and what they are used for.

This particular unit was assembled for a Simply Discus member, Ralph. It is a 5 stage RO/DI unit. The abbreviation RO/DI stands for Reverse Osmosis/Deionization. This particular type of water filtration unit is designed to remove ALL dissolved solid/ionic content from the feed water, leaving the product water's Total Dissolved Solids at 0 PPM.

When I refer to 5 stages, in this case they are:
  1. A 5 micron Polypropylene Prefilter (Sediment/Debris removal)
  2. A 1 Micron Carbon Block Prefilter (Dechlorination/Bacteria removal)
  3. A Dow Filmtec 1800 series Residental Reverse Osmosis element, 75 Gallons Per Day rating
  4. A Dowex C100E Mixed bed (cation/anion) deionization resin cartridge
  5. A Granulated Activated Carbon Polishing Filter

In this case the two prefilters do the job of removing most of the debris and bacterial content of the feed water and perform the critical task of removing water treatment chlorine from the feed water. As you may or may not know, chlorine destroys RO membranes very quickly.

Photo 1: Here is a photo of the three filter canisters that will be used in the construction of the unit. The first two from the left will be prefilters and the last one, the DI unit. These canisters are standard 10" which means they are designed for 9.75" filter elements. 9.75" is industry standard.

Note the use of clear canisters, which allows the user to monitor the condition of the prefilters/DI.

The canisters are placed in order and the feed ports are lined up so the input and output sides are matched properly (outputs connected to inputs).

Photo 2: Next, I use teflon tape to wrap the threads of all the fittings that will be used on the unit. I use John Guest Speedfit (tm) fittings on all aspects of the RO unit. This type of fitting allows quick assembly and ease of maintenance. The tape keeps the fittings from leaking.


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