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Chemical Character of Ground Water
The chemical character of the ground water in Osage County is shown in Table 4 by the analyses of 33 samples of water collected from wells and test holes. The analyses are given in parts per million. Factors for converting parts per million of mineral constituents to equivalents per million are given in Table 5. These water samples were collected from the principal water-bearing formations and from different parts of the county as evenly distributed as possible. Table 4 includes analyses of three public water supplies. All 33 samples of water were analyzed by Howard A. Stoltenberg, Chemist, in the Water and Sewage Laboratory of the Kansas State Board of Health.
Table 5--Factors for converting parts per million of mineral constituents to equivalents per million
| Cation | Conversion factor | Anion | Conversion factor | |
|---|---|---|---|---|
| Ca + + | 0.0499 | HCO3 - | 0.0164 | |
| Mg + + | 0.0822 | SO4 - - | 0.0208 | |
| Na + | 0.0435 | Cl - | 0.0282 | |
| NO3 - | 0.0161 | |||
| F - | 0.0526 |
Dissolved Solids
When water is evaporated, the residue consists mainly of the dissolved mineral constituents but may contain a little organic matter and water of crystallization. Water containing less than 500 parts per million of dissolved solids generally is satisfactory for domestic use, except for difficulties resulting from its hardness, or in some places, excessive iron content. Water containing more than 1,000 parts per million of dissolved solids may include enough of certain constituents to produce a noticeable taste or to make the water unsuitable in some other respect. The amount of dissolved solids in 28 samples of ground water from Osage County ranged from 278 to 70,900 parts per million (Table 4); about one-third of the samples for which dissolved solids were determined contained less than 1,000 parts per million.
Hardness
Hardness of water is commonly recognized by its effects when soap is used with the water. Calcium and magnesium cause nearby all the hardness of water and are the active agents in the formation of the greater part of scale formed in steam boilers and other vessels in which water is heated or evaporated.
In addition to the total hardness, the table of analyses shows the carbonate and noncarbonate hardness. Carbonate, or temporary, hardness can be removed almost entirely by boiling. The noncarbonate hardness is due to the presence of sulfates or chlorides of calcium a magnesium; it cannot be removed by boiling and is sometimes called permanent hardness. (The two types of hardness have the same reaction when the water is used with soap.)
Water having a hardness of less than 60 parts per million is rated as soft and is seldom treated to remove hardness. Hardness between 60 and 120 parts per million increases the consumption of soap but does not seriously interfere with the use of water for most purposes. Hardness above 120 parts per million can be noticed by anyone, and if the hardness is about 200 parts per million or more the water is sometimes softened for household use or cisterns are installed to collect soft rain water. Where municipal supplies are softened, the hardness is generally reduced to between 80 and 100 parts per million.
The hardness of 28 samples of ground water collected in Osage County ranged from 22 to 12,200 parts per million (Table 4).
Iron
Iron is generally dissolved in small quantities in most natural ground water. If water contains much more than about 0.1 part per million of iron, part of the iron may precipitate as a reddish sediment. Iron in excess of 0.3 part per million is undesirable as it may cause stains on cooking utensils, bathroom fixtures, and clothing or give a disagreeable taste to the water.
The iron content of 28 samples of ground water collected in Osage County ranged from 0.05 to 11.0 parts per million. All but 4 of the samples contained more than 0.1 part per million; about half the samples contained 0.3 part per million or less.
Fluoride
The fluoride content of water to be drunk by children should be known because of the effect excessive fluoride may have on their teeth. The dental defect known as mottled enamel may appear on the teeth of children who drink water containing excessive amounts of fluoride during the period of formation of their teeth. Teeth affected with mottled enamel have white chalky spots on them or in severe cases may have brown stains or may be pitted.
Water containing 1.7 to 1.8 parts per million of fluoride is likely to produce mottled enamel in about half the children continuously using such water, but the mottling would be largely of the very mild and mild types (Dean, 1936). Fluoride contents up to 1.5 parts per million cause little difficulty, and for that reason the U.S. Public Health Service (1946) has set that figure as its limit. The optimum fluoride content is about 1 part per million (Dean, 1938).
The quantity of fluoride in ground water in Osage County, except some of the ground water obtained from sandstone, is generally less than 1.5 parts per million (Table 4).
Nitrate
In Kansas many of the individual domestic water supplies have dissolved nitrates (NO3) in concentrations large enough to cause cyanosis of infants if the water were used in the preparation of a baby's formula. For this reason the nitrate content of water to be used by infants should he known. A concentration of 90 parts per million of nitrate as NO3 in drinking water is considered by the Kansas State Board of Health as being dangerous to infants, and some authorities recommend that water containing more than 45 parts per million should not be used for formula preparation. Metzler and Stoltenberg (1950, p. 194) state:
"The nitrates are converted to nitrites and absorbed by the blood, where they destroy its oxygen carrying properties. The blood becomes chocolate brown, the skin develops a blue color, and death may result from oxygen starvation."
Concentrations of nitrate found in ground water generally do not cause cyanosis in older children or adults but may have other adverse effects (Young, 1911).
Because of the soluble nature of natural nitrate minerals and the special conditions necessary for their accumulation, it seems likely that little nitrate is derived from nitrate-bearing rocks in the water-bearing formations. Soil nitrogen in the form of nitrate and ammonia salts probably are the chief source of nitrates found in ground water. Other sources of nitrate are barnyards, cesspools, and privies, which may also contribute dangerous bacteria to ground water.
Shallow dug wells are generally more susceptible to nitrate contamination than are deeper drilled wells. Nitrate concentrations seem to show seasonal variations, being highest in the winter season and lowest during the growing season of late spring and summer (Metzler and Stoltenberg, 1950, p. 202).
Of the 33 samples analyzed, 17 contained more than 45 and 14 contained more than 90 parts per million of nitrate (NO3). The nitrate content of the 33 samples ranged from 0.3 to 540 parts per million.
Sulfate
Sulfate (SO4) in ground water is derived chiefly from gypsum and the oxidation of iron sulfides. Sulfate occurring in ground water as magnesium sulfate (Epsom salts) and sodium sulfate (Glaubers salts) in excess of about 500 parts per million may have a laxative effect on persons not accustomed to drinking water containing large amounts of sulfate.
Chloride
Chloride in ground water may be dissolved in small quantities from sedimentary rocks, from connate waters in the sediments, or from sewage. Chloride has little effect on the suitability of water for ordinary use unless the quantity is enough to give the taste of salt. Chloride in excess of about 250 or 300 parts per million can be detected by persons having a sensitive taste. Water high in chloride is corrosive to many metal surfaces.
Sodium chloride is the chief constituent of the ground water in deep aquifers (200 feet or more in depth), which prevents use of otherwise adequate supplies of ground water in some parts of the county.
Sanitary Considerations
The analyses of water (Table 4) show only the amounts of dissolved minerals and do not indicate the sanitary quality of the water. Well water may contain mineral matter that gives the water an objectionable taste, but may be free from harmful bacteria and safe for drinking. Other well water, good tasting and seemingly pure, may contain harmful bacteria. Excessive amounts of certain dissolved minerals, such as chloride or nitrate, may indicate pollution.
A dug well generally is more likely to become contaminated than a properly constructed drilled well, because the opening at the top of a dug well may not be covered adequately and, therefore, not as effectively protected from surface water. A well should not be near possible sources of pollution such as privies, septic tanks, sewer drains, and barnyards.
Recommended sanitary types of construction and suggestions for locations and pump installations for cisterns and dug and drilled wells can be obtained from the Kansas State Board of Health.
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Kansas Geological Survey, Geology
Web version April 2002. Original publication date May 1955.
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