THE WATER WE DRINK…

Pre-Purchase Considerations

REVERSE OSMOSIS TOPIC LINKS:
Impurities Removed by R.O.
Measuring R.O. Effectiveness
Disadvantages of Reverse Osmosis
Equipment used in RO system
RO Purchase, Operational, Etc. Costs
Pre-Purchase Considerations

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Also See: R.O. Defined
(How Reverse Osmosis Works)

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And: Testing Your Water Supply

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Some of the factors that should be investigated are:

• The contaminant(s) involved and their initial concentration(s).
• The water supply rate, or whether the system will deliver enough water to meet normal daily drinking and cooking requirements.
• The rejection rate, or the percentage of contaminants to be removed by the membrane.
• The water pressure required to meet the supply and rejection rates. That is, can this unit be operated on the normal operating pressure of a home water system or will a booster pump be required?
• How can the system’s performance be monitored? That is, how can leaks or other problems be detected or how is the time for servicing or replacement determined? Some systems have built-in monitors, but many do not. Conductivity meters, pressure gauges and other devices can be used to detect problems where monitors are not included. Where coliform bacteria or other special contaminants are a known or suspected problem, periodic testing is recommended.

3. Storage Tank: Most RO units supply treated water at very low rates so a storage tank of 2 to 5 gallons is used to provide a suitable supply. These units are pressurized to produce an adequate flow when the tap is open. Under sink storage requires minimum pressure to deliver water. Other locations may require increased delivery pressure which may reduce membrane performance.

4. Post-Filter: The main reason for postfiltration is to remove any undesirable taste and any residual organics from the treated water. Usually a carbon filter is used for this purpose. Where a carbon filter is used as a part of the prefiltration step, postfiltration is normally eliminated.

5. Delivery Tap: A separate delivery tap for the treated water is used so that both treated and untreated water are available.

6. Other: No special controls are required on most systems since they operate by the use of pressure-sensitive switches, check valves, or flexible bladders. Shut-off valves are important to conserve water during low use periods. Monitoring gauges or servicing lights are becoming increasingly common and assist greatly in knowing whether the system is or isn’t working.