Here in NH, lots of people with wells have iron in their water. The
question often arises as to how to filter this stuff out.
Actually, iron (the red, visible kind) is easy to filter. Because of
electrostatic attraction, this type of iron wants to attach to
something - anything. You could run rusty water down a 2" pipe (long
pipe, very very long) and it would come out clean at the other end.
So, with this in mind, avoid using filters with a small micron rating.
Larger is much better to avoid premature clogging.
In my house, I use a 1.5 cu.ft. automatic backwashing filter filled
with a medium called "Filter Ag". It has a 20 micron size rating and
it works slick. The water is sparkling clean.
Now here's the rub. Water from my well has TWO kinds of iron in it.
The first kind is ordinary rust which, as I mentioned, is easy to
filter out. The second kind, is disolved iron which is clear. This
cannot be filtered out. So what to do?
This disolved iron must be oxidized so that it becomes ordinary rust
which can be filtered out. There are several ways to do this: (1)
Bubble air through the water. Municipal water systems sometimes do
this. Tough for a homeowner though. (2) Add a tiny amount of Chlorox
bleach. The bleach gives up oxygen molecules to oxidize the disolved
iron and the left-over bleach molecule (minus the oxygen) becomes an
ordinary table salt molecule. Since we're talking tiny amounts here,
the salt left in the water is trivial - almost unmeasurable.
This is the method I chose and it works. A special chemical injection
pump is used for the bleach, plus you need a large (I use 120 gal)
retention tank to allow adequate reaction time. This tank is in
addition to the regular bladder water tank you need for a well system.
All of this is followed by the filter.
(3) You can buy a filter that uses greensand for the medium. This
avoids having to use a chemical pump and retention tank but, you have
to periodically recharge the greensand with potassium permanganate.
Not for me thanks.
I hope this info helps someone.