Reverse Osmosis Water Filters Buyer's Guide
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  We review, analyze and compare the best water filters in the industry including reverse osmosis systems, faucet filters, water distillers, pitcher filters, whole house filters, water softeners, shower filters, bottled waters and more.

History of Reverse Osmosis


The natural process known as osmosis was first discovered back in 1748 by Jean-Antoine Nollet, a French clergyman and physicist. In his experiments, Nollet used a pig’s bladder as a membrane to show that solvent molecules from low solute water could flow through the bladder wall into a higher solute concentration made of alcohol. Thus, he became the first person to demonstrate the process by which a solvent can pass selectively through a semi-permeable membrane through the process of natural osmotic pressure.

Jean NolletJean-Antoine Nollet

For the next 200 years, there was little progress in the study or application of the osmosis process as it became just a curiosity known to laboratory scientists. This all changed in the late 1940s when researchers from American universities began to experiment with different technologies looking for an effective way to desalinate sea water. Saline water conversion was an important goal during those years, evidenced by the Kennedy administration’s slogan of, “go to the moon and make the deserts bloom”. A real breakthrough came in 1959 when two researchers at UCLA, Sidney Loeb and Srinivasa Sourirajan, produced a functional synthetic RO membrane from cellulose acetate polymer. Pressure was applied to a body of high solute water to force it against the membrane which acted as a filter that allowed only water molecules to pass through. This engineered membrane was able to reject NaCl (salt) and TDS while still allowing fresh water to pass at a decent flow rate to produce purified, potable water. What made it more remarkable was the fact that the membrane was durable and could operate under realistic water pressure making it highly applicable for water purification applications. The process became known as reverse osmosis, due to the fact that it works in reverse of the natural osmotic process.

osmosis process

In the 1960s, the world’s first commercial RO plant was built in Coalinga, California with the help and direction of Joseph W. McCutchan and Sidney Loeb. Operation on this pilot program began in 1965 and it attracted the attention of scientists and governments around the world with the hope that one day sea water desalination would be possible. While the Coalinga plant was able to purify up to 6,000 gallons a day, their focus was primarily on brackish groundwater which is much simpler than seawater which could be up to 10 times saltier. However, other pilot plants in La Jolla and Firebaugh California were working on membranes that could treat seawater and agricultural runoff water and their efforts would eventually lead to the wide variety of membrane technologies which are now used in many different industries.

Today, reverse osmosis technology is used in thousands of different processes and applications around the world for much more than just purifying water. Large reverse osmosis processing plants now provide much of the clean water used by some cities and even small countries. While few people know about the history of reverse osmosis, this technology is one of the most widely used and vitally important scientific achievements in human history, right up there with the moon landing.