> BTW, can anyone explain to me the differences between distilled water,
> deoinized water and filtered water?
>
> Thanks a lot!!
>
> David
Dave,
I've been involved with the design and installation of some specialized
water treatment systems aimed at producing high purity water. The
following boils down (pun intended) a lot of information into what I hope
answers your question.
Distilled water is made by boiling water and then condensing the steam back
into water again. It removes everything from the water except materials
that have boiling points above that at which the still is operated at. In
a practical sense, distillation is assumed to remove everything but
organics with vapor pressures at or less than water.
Deionization in a nut shell is your home water softener. That is a bit
oversimplified but not too far from the mark. Water is passed through a
resin column which is designed/engineered to remove targeted ions down to
a specified level. The resin can be selective for specific applications
such as defluoridation or of a general type as used in a home softener.
In general the water is not as pure as distilled water but the cost to
deionize is much lower than distillation.
Filtration is a whole basket of different things. You can micro filter
which means a filter element of .2 microns which removes all living matter
(except viruses if the things are actually living?). On the other hand,
you can carbon filter which actually chemically removes, through weak
bonding, almost all organics. Actually if designed with enough contact
time, activated carbon will remove all detectable organics.
In addition, there is a process called reverse osmosis which purifies the
water by forcing it through a a semipermeable membrane. This is can be
thought of as a form of filtration.
Water treatment is done to creat highly purified water as well as clean up
discharge waste. It is common to combine various treatments.
The purest water is produced through carbon filtering followed by
distillation. The activated carbon removes all of the low vapor pressure
organics which allows the still to remove everything else which furnishes
pure water.
Back to the basement dehumidifier. If it is completely cleaned out then
the water collected from it could be passed through a carbon filter and a
.2 micron filter and you will have very pure water. As it turns out, the
back packer's filters, sold in sporting goods stores, typically contain
both of these filter types. Lastly, activated carbon does collect all
organics and it will begin to grow the local fauna in a short time
(commercial operations steam sterilize these filters on a routine basis).
Knowing all of the above, I still just buy my distilled water at the
grocery. Unfortunately, the city water in Columbus Ohio is very hard so
I use distilled for all process steps. Not a big cost item when all is said
and done.
Sincerely, Art
Art Chakalis
Columbus, Ohio, USA