Reverse osmosis (RO) is one of the most convenient and effective filtration methods available. RO membranes can usually remove between 96 – 99% of most contaminants, including salts, minerals, dyes, particles, bacteria, and hazardous metals.
In reverse osmosis, contaminants are separated from water by forcing it through a semi-permeable membrane. This membrane acts as a physical barrier to almost all molecules with a molecular weight greater than 200 grams/mole. For example, the membrane may allow passage of water molecules but block molecules of dissolved salt. These unwanted molecules are retained by the membrane while the ultra-pure water continues on for use or further treatment. This is the same technology used to make bottled water and is the only technology capable of desalinating sea water to be made into drinking water.
Non-RO water filters are much less effective. They can filter out coarse particles, sediments and elements but anything finer including most dissolved substances cannot be filtered out. This will result in a lower quality of filtered water compared to RO filtration.