Hello again, Carolyn!
A Google search on this subject turns up many sites that are selling
something. I am always reluctant to rely on information acquired from
a commercial site, so I did not include that kind of material in my
research. Unfortunately, search engines are not yet smart enough to
automatically eliminate commercial sites from search results, so this
was a filtration process that relied upon my mind as a filter, rather
than Google's estimable artificial intelligence. Come to think of it,
that's what Google Answers is really designed for: to place a human
mind into the search effort.
I've found several articles that discuss reverse osmosis and sodium.
For reasons of copyright, I am posting only brief excerpts below. You
may want to read these articles in their entirety, since they contain
quite a bit of information that may be of use to you.
"A technique used in processes requiring high-quality, purified water,
such in semiconductor processing or biochemical applications, is
reverse osmosis. It can be used to treat boiler feedwater, industrial
wastewater, or process water. Reverse Osmosis is a water purification
technique that reduces the quantity of dissolved solids in solution...
It is necessary to establish feedwater quality guidelines to optimize
system performance and prevent the three main problems associated with
RO: scaling, fouling, and degradation of RO membranes...
Rensselaer Polytechnic Institute: Introduction to Reverse Osmosis
http://www.rpi.edu/dept/chem-eng/Biotech-Environ/MISC/biotreat/reverseo.html
"Reverse osmosis (RO) has become a common method for the treatment of
household drinking water supplies. Effectiveness of RO units depends
on initial levels of contamination and water pressure. RO treatment
may be used to reduce the levels of:
1. Naturally occurring substances that cause water supplies to be
unhealthy or unappealing (foul tastes, smells or colors).
2. Substances that have contaminated the water supply resulting in
possible adverse health effects or decreased desirability.
RO systems are typically used to reduce the levels of total dissolved
solids and suspended matter. The principal uses of reverse osmosis in
Minnesota and the Dakotas are for the reduction of high levels of
nitrate, sulfate, sodium and total dissolved solids.
RO units with carbon filters may also reduce the level of some SOCs
(soluble organic compounds) like pesticides, dioxins and VOCs
(volatile organic compounds like chloroform and petrochemicals). An RO
unit alone may not be the best solution for these types of
contaminants, but installing a properly design-ed RO unit to reduce
the levels of other contaminants may provide a reduction in SOCs and
VOCs."
North Dakota State University: What impurities will reverse osmosis remove?
http://www.ext.nodak.edu/extpubs/h2oqual/watsys/ae1047w.htm
"Reverse osmosis (R/O) is a water treatment process in which water is
forced through a semi-permeable membrane that has very small holes or
'pores'. Clean water passes through and impurities that are too big to
pass through the membrane are left behind and flushed away...
Reverse osmosis can remove dissolved solids, salts, minerals that
cause hardness, organic chemicals and other impurities. It can improve
the taste of water for people who do not like the taste of dissolved
mineral solids.
Treated water will not produce scale in kettles and coffee makers.
Because sodium and potassium are removed, people on a medically
prescribed sodium- or potassium-restricted diet may benefit. R/O units
may also remove contaminants such as chromium, mercury and nitrates...
R/O units will not operate efficiently at water pressures below 40-45
psi. If the pressure is too low, as in the case in many rural private
systems; in an apartment on a higher floor of a building; or at the
end of a long water line serving several units, a booster pump should
be installed to increase pressure."
Canada Mortgage and Housing Corporation: Reverse Osmosis - Water Treatment
http://www.cmhc-schl.gc.ca/en/burema/gesein/abhose/abhose_068.cfm
"Q. Is there a household water treatment device which will remove the
potentially dangerous, health-related metal impurities from water for
drinking and cooking?
A. Yes. Several systems are small enough to be installed under a
kitchen sink to supply a special faucet, ice cubers, etc., with highly
purified water for cooking and drinking. These systems operate on
well-known water purification principles, such as demineralization and
reverse osmosis, and will substantially remove not only the metals,
but laxative sulfates, sodium and other minerals from the water...
If you suffer from hypertension or are on a sodium-restricted diet,
you should consult your doctor about the proper water for drinking.
Since most hard waters also contain sodium, your doctor may recommend
that you drink sodium-free packaged or bottled water, or remove sodium
from your water by demineralization or reverse osmosis."
Canadian Water Quality Association: Soft Water and Your Health
http://www.cwqa.com/html/consumer6.html
"Will Reverse Osmosis remove sodium from water?
Yes. The initial application of the reverse osmosis process was
removal of salt (desalinization) from sea water for use as drinking
water aboard naval vessels. This application has been expanded to
include large, land-based facilities supporting entire communities.
This may prove to be very beneficial to someone on a low sodium diet."
The Whole Truth: Reverse Osmosis F.A.Q.
http://www.thewholetruth.org/Res_WP_RO_FAQ.htm#9
In conclusion, reputable reference sources indicate that reverse
osmosis will remove sodium and many other minerals from water. The
main caveats are that the membrane and pre-filters must be kept in
good condition, and that the water pressure must be kept above 40
pounds per square inch. The consumption of water is increased
significantly by an RO unit, which may be a concern in areas where
water is rationed, or is costly.
Water purification is not my research specialty, but, in my layman's
opinion, RO seems to have many more pluses than minuses. I would love
to have a reverse osmosis unit for my household, and I fully intend to
purchase one (as well as a water softening unit) when my budget
permits it.
Regarding the matter of testing your water, there are numerous labs
that can do this for you. Here is a list of water testing laboratories
in the Clearwater Beach area. Some of these firms have websites that
can provide more info on the services that they offer:
Superpages: Water Testing Laboratories, Clearwater Beach
http://phonebook.superpages.com/yellowpages/C-Water+Testing+Laboratories/S-FL/T-Clearwater+Beach/
There are salt test strips which are designed for swimming pool
owners, but they are only accurate at detecting rather large amounts
of sodium (in the vicinity of 1000 ppm and up, which is VERY salty
from the standpoint of drinking water - most tap water contains 100
ppm or less). I don't think test strips would be useful for your
purposes. To be honest, unless you have reason to suspect the
integrity of your RO membrane and/or filters, I doubt that testing is
really necessary, since a reverse osmosis unit, if it is doing its
job, can be counted upon to remove sodium from your water.
Google search strategy:
Google Web Search: "reverse osmosis" + "remove OR removes" + "sodium"
://www.google.com/search?hl=en&ie=UTF-8&q=%22reverse+osmosis%22+remove+OR+removes+sodium
Google Web Search: "clearwater beach" + "water" + "testing"
://www.google.com/search?hl=en&ie=UTF-8&q=%22clearwater+beach%22+water+testing
Google Web Search: "home" + "water test OR tests" + "sodium"
://www.google.com/search?hl=en&ie=UTF-8&q=home+%22water+test+OR+tests%22+sodium
I hope this helps! If I'm off target, or if anything additional is
needed, please let me know, and I'll get back to you as soon as I can.
Best always,
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