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The reverse osmosis process contains several downsides which make it an inefficient and ineffective means of purifying drinking water. The small pores in the membrane block particles of large molecular structure like salt, but more dangerous chemicals like pesticides, herbicides, and chlorine are molecularly smaller than water (Binnie et al, 2002). These chemicals can freely pass through the porous membrane. For this reason, a carbon filter must be used as a complimentary measure to provide safe drinking water from the reverse osmosis process. Such chemicals are the major contaminants of drinking water after municipal treatment.

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Another downside to reverse osmosis as a method of purifying drinking water is the removal of healthy, naturally occurring minerals in water. The membrane of a reverse osmosis system is impermeable to natural trace minerals. These minerals not only provide a good taste to water, but they also serve a vital function in the body’s system. Water, when stripped of these trace minerals, can actually be unhealthy for the body.

Reverse osmosis also wastes a large portion of the water that runs through its system. It generally wastes two to three gallons of water for every gallon of purified water it produces. Reverse osmosis is also an incredibly slow process when compared to other water treatment alternatives.

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Volatile gases such as oxygen and hydrogen sulfide will pass through reverse osmosis membranes. Some organic substances with low molecular weight can also pass through the membrane. Some of these organic substances are suspected of being cancer causing; fortunately these substances are rarely found in Alberta water. The activated carbon filters used in most reverse osmosis units can remove most organic substances anyway. Bacteria can also "grow through" reverse osmosis membranes leading to possible bacterial growth in the postfilter and water storage tank.

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Interestingly, reverse-osmosis membranes aren’t all capable of removing the same-size particulates. In fact, the pores (tiny openings) in various R/O membranes are rated as to the largest matter that can pass through them. For example, a typical membrane used in residential units might have a rating of 0.01 microns. Although water molecules under pressure are able to pass through these minute openings, the holes are just too small to let solids over 0.01 microns pass through. (In reality, a membrane will not have all pores of the same size. The pores in a membrane with a rating of 0.01 microns might range from 0.001 up to 0.01 microns.) When water passes through an R/O membrane, a great deal of the dissolved minerals, heavy metals, asbestos, dirt particles, radioactive particles, fluoride and bacteria will be left behind. R/O units can be so capable that they’re usually able to remove an estimated 80-95% of all dissolved solids from the water they treat.

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R.O. is a process that exposes water under pressure to a semi-permeable membrane with a very fine pore structure. The membrane acts as a barrier and will physically block extremely small particles, down to 0.009 microns in size. The idea is that anything larger than a water molecule will be blocked and washed away. R.O. filters also require the use of carbon pre and post filters to remove free chlorine from the input (pre-filter) and taste, odor, and many synthetic chemicals like herbicides and pesticides, that are smaller than a water molecule, from the output (post filter).

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and this one:

http://www.aquaprosolutions.com/index_files/AquaPro_water_facts.htm



thats all i could come up with on this subject, i couldnt find any sources for the binnie et al. 

leftysurprise said:

thats all i could come up with on this subject, i couldnt find any sources for the binnie et al. 

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