PUB00055

• Year: 1961
• Title: Public Water Supplies of Colorado
• CWCB Section: Interstate & Federal
• Author: Gregg, Meyer, Targy, Moulder
• Description: Summary of statistical data describing the source, treatment and volumes of water used for public supplies by Colorado cities and towns
• Publications - Doc Type: Tech Report

people suffering from kidney or heart diseases (Welsh and Thomas,
1960, p. 295). Chloride cannot be removed from water by any
practical methods at the present time.

Nitrate is rarely present in significant quantities in
natural surface waters but may be present in ground water. Because
nitrate is an end product of organic decay such as is found in
sewage, unusually high concentrations may be indicative of pollu-
tion. concentrations of nitrate in water are becoming a problem
in some agricultural areas where chemical fertilizers such as
ammonium nitrate are being used. Methemoglobinemia, a cyanotic
condition, may develop in infants who are fed water containing high
concentrations of nitrate. Some investigators (comly, 1945, p. 112-
116) recommend 44 ppm as a safe upper limit for nitrate in water
used for infant feeding.

Water for Sanitation

One of the objectionable characteristics of water used for
sanitation is hardness, which is caused principally by the calcium
and magnesium in the water. Because calcium and magnesium cause
soap to precipitate, hard waters require large amounts of soap
for efficiency in laundry and cleaning, and the unsightly deposits
that are formed may remain on the surface of articles washed in
the water. The use of synthetic detergents has reduced the
problems in sanitation, but detergents can cause other problems
in water-treatment and sewage-treatment plants. Detergents in
water hinder flocculation and filtration of impurities and cause
excessive foaming.

Although no definite limits for hardness have been established,
the following gradations are generally recognized:

Hardness
as CaCo)
ppm
Less than 60

Ratinq

Suitability

Soft. .

. . . . . .

.

Suitable for many uses
without further softening.
usable except in some
industrial applications.
softening required by
laundries and some other
industries.
Requires softening for
most uses.

60-120
121-200

Moderately hard .

.

Hard. . . .

. . .

. .

More than 200

very hard' .

. . . . . .

The hardness of water may be reduced economically by several
general methods, such as the lime-soda softening process and the
sodium-zeolite softening process. It can be reduced to nearly
zero: however, many municipalities prefer to reduce it only to a
level at which the water can be used satisfactorily.

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