A reverse osmosis system is beneficial in certain industries. De-mineralized water is good for processing film, washing cars and metal parts do not rust as quickly in it. But, the trace minerals that exist naturally in water are good for you. That's why experts advise against drinking distilled water. Distillation removes minerals, but like the reverse osmosis systems, it does not remove the chemicals.


The filter or membrane used in a reverse osmosis system has pores small enough to remove minerals and some other compounds from the water, but most of the toxic chemicals are microscopic in size, smaller than the size of a water molecule. So, if the water can get through the membrane, then so can the chemicals.


Some salespeople talk about reverse osmosis systems like they are state of the art, but it's really older technology. In the newer filtration systems, activated carbon and other mediums are used to trap contaminants.


In a reverse osmosis system, water under high pressure is forced through a membrane. The membranes break down. Algae can grow on them. There can be gaps around the edges. It's just not a good system. But, if you're still not convinced, look at the cost.


Reverse osmosis systems cost users 18-24 cents per gallon. The newer dual stage filters cost about 10 cents per gallon. A reverse osmosis system in the home is difficult to install, requires more maintenance and replacing the membrane is more complicated. The membranes also cost more than replacement cartridges for carbon filters.