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Almost all
natural waters contain chloride and sulfate ions. Their
concentrations vary considerably according to the
mineral content of the soil in any given area.
In small
amounts they are not significant. In large
concentrations they present problems.
Sulfates
can be more troublesome because they generally occur in
greater concentrations.
Low to
moderate concentrations of both chloride and sulfate
ions add palatability to water. In fact they are
desirable for this reason. Excessive concentrations of
either, of course, can make water unpleasant to drink.
The U.S.
Public Health Service Drinking Water Standards recommend
the same maximum concentration - 250ppm - for each of
the chloride and sulfate ions.
Water
containing calcium sulfate ions is likely to have a
characteristic taste…somewhat bitter and astringent.
In fact it has been compared to the way dissolved gypsum
might taste in water.
When 30
to 40 grains per gallon of calcium sulfates are
dissolved in water most people can detect the taste.
If equal
amounts of magnesium sulfate or sodium sulfate are
dissolved in water, the taste would not be noticeable.
Both possess definite laxative effects in concentrations
above 30 grains per gallon. In this way they can be
troublesome especially to people not accustomed to such
water.
Chlorides
give water a salty taste. At what concentrations this
becomes noticeable depends on the individual. In large
concentrations chlorides cause a brackish, briny taste
that definitely is undesirable.
Although
chlorides are extremely soluble, they possess marked
stability. This enables them to resist change and to
remain fairly constant in any given water unless the
supply is altered by dilution or by industrial or human
wastes.
Both
chlorides and sulfates contribute to the total mineral
content of water. As indicated above, the total
concentration of minerals may have a variety of effects
in the home.
*See De-contamination
by reverse osmosis for removal of chlorides and sulfates
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