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Alkalinity
of water may be due to the presence of one or more of a
number of ions. These include hydroxides, carbonates and
bicarbonates.
Small
amounts of carbonates are found in natural water
supplies in certain sections of the country, rarely
exceeding 3 0 4 gpg. They may also be found in water
after treatments such as lime-soda ash softening.
Bicarbonates
are the most common sources of alkalinity. Almost all
natural supplies have a measurable amount of this ion,
ranging from 0 to 50 gpg.
Moderate
concentrations of alkalinity are desirable in most water
supplies to balance the corrosive effects of acidity.
However, excessive quantities cause a number of
problems.
You
probably will not notice an alkaline condition due to
bicarbonate ions except when present in large amount. In
contrast you should readily detect alkalinity due even
to fairly small amounts of carbonate and hydroxide ions.
Strongly
alkaline waters have an objectionable "soda"
taste. The U.S Public Health Service Drinking Water
Standards limit alkalinity only in terms of total
minerals (500 ppm) and the limitation on taste.
Highly
mineralized alkaline waters also cause excessive drying
of the skin due to the fact that they tend to remove
normal skin oils.
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