Reverse Osmosis does not effectively reduce VOCs, endocrine disrupters, pesticides, or trihalomethanes. The reverse osmosis membrane can also be sensitive to certain water characteristics. This type of filter is specially engineered for specific contaminant reduction. These filters show a high performance against the specific contaminants, but not against other contaminants. Water softeners are neither filters nor purifiers and are used only to change the water hardness.
Softeners put sodium into the water in exchange for magnesium or calcium ions.
It is recommended that water softeners be bypassed when installing a water filter. Most softeners must be professionally installed. UltraViolet Treatment Water passes through a chamber where it is exposed to UltraViolet radiation. Very turbid water can reduce the effectiveness of this type of treatment. This treatment is effective against many bacterial contaminants, but is not effective in reducing cryptosporidium.