What Does "RO" Mean?

RO stands for reverse osmosis, the reverse of energy's natural flow from higher to lower levels of concentration. In normal osmosis, pure water dilutes impure water due to pure water's higher energy level. Reverse osmosis involves applying pressure (mechanical energy) to drive pure water out of impure solutions.

HOW DOES IT WORK?

This applied energy is normally provided by a medium to high pressure water pump, which overcomes energy differences (osmotic pressure) and drives feed water through a porous, semipermeable membrane made of polymeric material. Semipermeable means the membrane will pass pure water through, but will reject most dissolved impurities.



This RO system utilizes a low pressure membrane so that a pump is not necessary; it runs on line pressure. Although the RO membrane contains very small pores, which allow pure water passage, the system is not perfect, so a slight amount of feed water impurities will pass through the membrane with the purified water. The percentage passing depends on such things as membrane polymer type, membrane condition (e.g. age, cleanliness), driving pressure (energy), and temperature, but is normally less than 5% of feed water content. That means the membrane is typically 95% efficient. If your raw (feed) water had 100 parts per million (PPM) of dissolved solids, the product (purified) water would have only 5 PPM. Because the hard water minerals are rejected along with bacteria and other contaminants, the product water is also softened as though it had passed through a water softener, so you will get the same benefits when bathing or laundering. Reducing the amount of dissolved minerals in the product water by 95% means that there are fewer minerals left to create spots as water evaporates from the surface of your appliances, fixtures, and shower glass. RO water is also commonly used in car washes to eliminate spots, so you might want to arrange a hose bib to use for washing your coach or dingy. If we forced all feed water through the membrane, as we do a pre filter, it would rapidly become plugged up because it has such small pores. In order to prevent rapid plugging, some of the feed water is passed over the surface of the membrane to wash away the rejected solids, as in a cross flow filtration mode. Therefore, from one feed water stream, an RO machine produces one purified water stream called permeate, and a second stream called concentrate, brine, or reject. This system restricts the amount of reject water to about twice the product water. We refer to this as the recovery ratio; in this case the recovery ratio is 33% because we use 1/3 of the feed water and reject 2/3's.

HOW IS THE SYSTEM CONSTRUCTED?

Your RO system consists of two pre filters and the RO vessel. It will be installed so that you may connect a water source to it via an available connecting hose to the inlet of the first pre filter housing. The first pre filter is a 5 micron depth filter. The depth filter is made of spirally wound fibers in a manner such that larger particles are trapped at the surface, while the smaller particles are allowed to penetrate to the center of the filter, hence, the name "depth" filter. This filter is very important as it prevents particles larger than 5 microns from getting into and plugging up the RO membrane. The second pre filter is a 5 micron carbon block filter that eliminates chlorine. If chlorine is allowed to contact the membrane its life will be seriously shortened. After being filtered twice, the feed water is run through the RO membrane; the product water will then be diverted to your storage tank and the reject water will be routed to the drain.



WHAT KIND OF WATER CAN I USE?

This system is designed to be used on potable (drinking) water only. You can feel comfortable using water in most RV Parks as it is clean with the exception of minerals. If you feed the RO system dirty (visibly turbid) water you will plug up the filters rapidly and diminish the efficiency of operation. Subjecting the system to iron bearing water will foul the membrane and shorten its useful life. The best policy is to use clean drinking water only.

WHAT MAINTENANCE IS REQUIRED?

Maintenance will vary according to usage of the system; however, you should change the filters whenever there is a 5psi drop in pressure between the inlet gauge and the post filter (outlet) gauge. Such a drop is an indication that the filters are getting loaded with sediment. Typically, changing the 5 micron depth filter only will correct a pressure drop situation if you catch it early. If, after replacing it, you still have a pressure drop, you will need to change the carbon block filter also. We recommend you replace both filters annually. The system comes with a filter wrench to make the job easier.

HOW DO I KNOW THE RO SYSTEM IS WORKING?

You must have a total dissolved solids meter in order to measure the dissolved solids in the feed and permeate water to compare the two or calculate % rejection. A portable meter will cost $85.00, or, you can install our "before and after" TDS meter for about $60. As an alternative, you can send us two ounce samples of both feed water and permeate water (samples must be in a plastic or glass container witha non metalic lid). We will test the water and advise you the results. We suggest this be done at least annually.

HOW DO I WINTERIZE THE SYSTEM?

Winterizing is easy. Remove the filter bowls by rotating counterclockwise as viewed from the bottom (a filter wrench is provided), drain the housings and replace the housings without the filters. The filters may be discarded if you follow our advice to change them annually, or you may store them in a zip lock bag in a refrigerator (to prevent bacterial growth). We recommend you remove the membrane/housing assembly as a unit and store it in a refrigerated environment. The RO membrane and housing must be drained of all water. To drain water from the housing, stand it on end until all water has run out.



PHOTO SHOWING MEMBRANE BEING INSERTED INTO HOUSING.

Note the tetra seal on the left end of the membrane; it must be lubricated and, because of its shape, it will only go into the housing in one direction (see arrow). You should also lubricate the PVC ends of the membrane, as they fit inside of "O" rings in the end plugs.



PHOTO OF END PLUGS AND A "U" PIN

Note the end plug on the right has only one fitting in it; this is the plug for the incoming water (filtered water in). The plug with two fittings is for the permeate/waste water. Permeate comes out the 90 degree elbow