Carbon filters, registered as bacteriostatic by the EPA, have the pesticide silver in the filter. This does not mean that the EPA recommends, approves, or endorses the product. Studies on the effectiveness of bacteriostatic filters have shown unpromising results as to their ability to control bacterial growth. Further, a bacteriostatic carbon filter is not adequate to treat water that is microbiologically unsafe, such as fecally-contaminated water. RO units alone are not recommended for use on microbiologically unsafe water.
RO units have several disadvantages.
They typically waste about 75 percent of the tap water put into them. For one gallon of RO filtered water, it may take four gallons or more of tap water. Also, the tap on the storage tank flows more slowly than the tap on your regular faucet. The membranes on RO units are subject to decay and failure and must be replaced periodically. Follow the manufacturer's recommendations about proper maintenance and use.