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Re: R/O filters & well water

Colin wrote:
"It's worth mentioning that there are two types of filter material
available for RO filters. I don't have the info. in front of me, but the
normal one _must_ have chlorine in the water to preserve the filter
screen. The other type _mustn't_ have chlorine in the water as chlorine
destroys the filter, just make sure that you get the right type of
filter and have enough pressure for the filter. The excess water does
wonders for your garden - all those nitrates/phosphates etc."

Actually, I believe that there are more than 2 types of membranes available
but only TFC and CTA are used in residential installations.

TFC is more expensive and will usually do a better job of rejecting some
contaminants (like 90% rejection vs 50% rejection for some ions). It cannot
be used with chlorinated water UNLESS the water is first pre-treated with
Carbon (to remove the chlorine). Most commercial units which use TFC
membranes have this carbon prefilter inline.

CTA is generally less expensive and is subject to bacterial
degradation/contamination. It must be used on chlorinated water. CTA
membranes are not as efficient nor as effective as TFC membranes.

R/O units have come _way_ down in price over the past few years, as more and
more people buy them.

BOTH types of membranes require a certain amount of water pressure in order
to work effectively and efficiently. If you don't have sufficient pressure
you will need an auxilliary pump (which can easily be more expensive than
the R/O unit itself).

James Purchase