Reverse Osmosis Water Purifiers for Household uses

Reverse osmosis is a proven technology that has been used successfully on a commercial basis. One of the better known uses of RO is the removal of salt from seawater. Household RO units typically deliver small amounts (8 to 40 liters per day) of treated water and waste 8 to 15 times the amount of water treated. Reverse osmosis units remove many inorganic contaminants from household drinking water supplies. The removal effectiveness depends on the contaminant and its concentration, the membrane selected, the water pressure and proper installation.

RO units require regular maintenance and monitoring to perform satisfactorily over an extended period of time. Before purchasing an RO unit or any other water treatment equipment, purchasers should test their water to be certain that treatment is needed and that the equipment being selected is appropriate to the problem requiring treatment. All costs need to be considered when comparing competitive systems and when making purchase decisions.

How effective RO is depends on the initial level of contamination, and water pressure.  It is principally used to reduce the levels of Total Dissolved Solids (TDS) and suspended matter. 

RO systems are used in two applications - industrial and household water treatment.  The process involves pushing contaminated water at pressure through a semi-permeable membrane. The membrane has microscopic openings that allow water molecules, but not larger compounds to pass through. 

Some of the companies that make Household water purifiers for the Indian market using RO are Kent, EurekaForbes.  Kent makes models such as Grand, Pearl, Elite, Excell+ and Pride.  EurekaForbes makes models such as AquaSure RO.

Advantages of a RO System:

1. Very convenient for commercial usage, as a much higher percent of water is recovered.

2. Useful for places where there is a serious shortage of fresh water.

Disadvantages of a RO System: 

1. Wastage:  RO Systems waste a lot of water, as they recover anywhere from 5 to 20% of the total water.  The balance is discharged as waste water.  For commercial or industrial systems, much more is recovered. But for small, household systems it is not cost effective to recover more water.

2. Cost:  For example, for Kent Grand RO Purifier, the company charges Rs 1800 annual maintenance contract which does not include cost of filters and membranes.  Filters plus membrane costs about Rs 2000, which should be changed anywhere from a year to two years, of course depending on usage, type of water being treated etc. 

3.  The membrane is very sensitive, and should it be clogged or torn, it would not be purifying any water, but for most system users, it would be difficult to find out.  Some of the newer systems have built in alarms for such accidents.

Other Related Posts

Part I - Summary of Water Filters in India

Part 3 - Review of TATA Swach
Part 4 - UltraViolet (UV) Method of Water Disinfection