ro unit

[reefburnaby]

Hello,

Most household ROs are based on TFC membrane and they require non-chlorinated water to work reliable (the membrane has a tendency to self destruct with chlorinated water). This is why water must pass through a carbon block before it goes to the TFC and it is one of the reasons why we have to replace it fairly periodically)

Most RO membranes can filter out the large viruses and bacteria from the water. However, if the viruses/bacteria get trapped in the RO membrane, there is nothing to kill them. Remember, the city puts chlorine to kill these viruses, but we removed them to protect our TFC. Since our RO water is so clean, the bacteria/viruses should starve and die ? Nope...RO water still has tiny amounts of nutrients and it is sufficent for the bacteria/viruses to grow. After a couple of months, your TFC would be infested with viruses/bacteria and contaminate your filtered water.

However, since we add salt to our filtered water, most of these bacteria/viruses should die because most freshwater bacteria/viruses can not survive in salt water conditions. This is equivalent to freshwater dipping our saltwater friends.

The other common form of RO is based on CTA -- and it works with chlorinated water. But the problem with CTA is they are not as good at filtering water as TFC (higher percentage of phosphates pass through and etc) -- see Kent's website for details.

What to do ? Most people recommend placing a UV sterlizer at the last stage of the RO water filtering process. UV will kill most bacteria in the ROed water (not perfect though). Have you bought RO water from the store (say, Superstore ?) They are ROed, but they have a UV sterilizer at the end.

Want some more proof - Spectrapure sells a good product -- so why would they sell one of these :
http://www.spectrapure.com/kits_p2.htm http://www.purewaterexpress.com/faq.htm#7 http://www.actwin.com/fish/aquatic-p.../msg00335.html

So...if you are comfortable with drinking RO water (that could have bacteria in it), then bottoms up. If you must drink RO only water, most manufacturers recommend that you disinfect your RO filtration system once in a while. For drinking water, I'll stick with RO + UV or boiled water....

I am not a water expert, but due to the line of work I am in...my health is extremely important.

Titus, most RO membranes can filter down to 0.0001 microns, so I am not sure what you are refering to. Also, Kent sells a floss/carbon filter that works down to 1 micron -- so why bother with a 0.5 micron RO filter ?