Pros and cons of reverse osmosis

Are you a homeowner considering installing a reverse osmosis (RO) drinking water system?  Or maybe a buyer considering a home that has one?  Here are some basic facts to help you out.

RO was originally developed by the US Navy to convert sea water into drinking water for submariners.  RO operates by running water through a membrane that is big enough for water molecules, but not other compounds.  Some membranes have an electrical charge that helps reject chemicals.

The effectiveness of RO units depends on the initial amount of contaminants and water pressure.  RO may reduce the levels of naturally occurring substances that cause water supplies to be unhealthy or unappealing (i.e. taste, odor, and color).  RO systems are typically used to reduce levels of dissolved solids and suspended matter.  In Minnesota in particular, RO lowers levels of nitrate, sulfate, and sodium.  Some RO systems have carbon filters that reduce some levels of pesticides, dioxins, chloroform, and petrochemicals.

The main downside to RO is wasted water.  For every 5 gallons of drinking water produced, anywhere from 40 to 90 gallons of water enters the sewer.  Because the waste water has higher levels of contaminants, it is not practical to reuse it in a household system.

RO systems range in initial cost from several hundred to over a thousand dollars.  Typical maintenance fees run from $30 to $90 annually for replacement filters and membranes.  These costs are exclusive of additional water usage and sewer fees. 

Information in this article was sourced from North Dakota State University and Pure Water Products, LLC.


Posted by Andrew Leeth on 03/03/2010