### Top 5 Water Contaminants
Examine each of these analyses carefully now. Then consider the suggested solutions. Note the reasons given for these solutions. Perhaps other sound solutions come to mind.
**Water Analysis Example No. 1 ** |
Date Collected |
.................... |
8/14/83 |
Source |
.................... |
Well |
Date Analyzed |
.................... |
8/23/83 |
Appearance when drawn |
.................... |
Clear, odorless |
pH |
.................... |
7.5 |
Iron |
.................... |
0.2ppm |
Bicarbonate |
.................... |
11.3gpg |
Sulfate |
.................... |
3.5gpg |
Chloride |
.................... |
1.6gpg |
Total Anions |
.................... |
16.4gpg |
Calcium Hardness |
.................... |
10.5gpg |
Magnesium Hardness |
.................... |
5.3gpg |
Total Hardness |
.................... |
15.8gpg |
Calcium Bicarbonate |
.................... |
10.5gpg |
Magnesium Bicarbonate |
.................... |
0.8gpg |
Magnesium Sulfate |
.................... |
3.5gpg |
Magnesium Chloride |
.................... |
1.0gpg |
Sodium Chloride |
.................... |
0.6gpg |
*All values are reported as CaC0_{8} equivalent except pH and iron.
Study of Water Analysis No. 1 shows that the water is very hard according to the Water Quality Association's hard water classifications. While total hardness equals 15.8gpg, the total cations equal 16.4gpg. The sodium in the water (0.6gpg) accounts for the difference between total anions and the total hardness. The amount of iron, however, is negligible and would produce no staining of washables in the laundry.
A sound solution for treating this water would be the installation of an ion exchange softener of proper capacity on both the hot and cold water lines. The outdoor sillcocks should be bypassed. Where possible, the toilets could also be bypassed, as the amount of iron in the water is not sufficient to produce any appreciable staining.
The capacity of a unit necessary for the installation would depend on the number of people in the household and to some extent on the number of water using appliances. The type of model (manual, semi-automatic, or fully automatic) would be a matter of personal preference on the part of the buyer.
A look at Water Analysis Example No. 1 shows that the iron is reported in parts per million while all the hardness minerals are listed in terms of grains per gallon. Why is this practice followed? Primarily for convenience in reporting concentrations of minerals--some of which are found in water in abundance and some of which are found in only scant, or even trace, amounts.
Actually there are four basic units of measure used in water analysis work: parts per million (ppm) or milligrams per liter (mg/1); grains per U.S. gallon (gpg); equivalents per million (epm); and grains per imperial gallon (gpg imp).
To make a conversion from parts per million to grains per gallon, you simply divide the parts per million by 17.1 to convert to grains per gallon.
Thus...
milligrams per liter or parts per million |
= |
grains per gallon |
17.1 |
One word of caution: the term parts per million means one part in a million parts. Correctly, 1 ppm could be translated as one ounce in a million ounces of water, or one pound in a million pounds of water. On the other hand, it would be incorrect to interpret 1 ppm to mean one pound in a million gallons of water without first converting the figures. For obviously, pounds and gallons are not similar units of measure. In the same way, 1 milligram, or 1/1,000 of a gram, in a liter of water which weighs 1,000 grams, is 1 milligram per liter or 1 part per million.
The point-of-use water conditioning industry generally expresses hardness in terms of grains per gallon. This is done to avoid working with large figures in many instances. An exception would be trace substances which are expressed in terms of milligrams per liter. Another point to remember ... the minerals we are considering in these analyses are expressed in terms of hypothetical combinations in terms of grains per gallon or milligrams per liter as calcium carbonate (CaC0_{3}).
In order to make calculations for all the various hardness mineral compounds, the concentrations of the various ions must be expressed in equivalent units to permit direct addition and subtraction in analysis work. This is similar to the conversion of 113 and 114 to 4112 and 3112, respectively, to facilitate use of these fractions in addition and subtraction.
If it is stated that water contains minerals in the amount of 10 grains per gallon as CaCO3, these minerals may consist of calcium or magnesium carbonates, bicarbonates, sulfates or chlorides, or a combination of these compounds. But in every case, the combined concentration of these various hypothetical combinations is chemically equivalent to 10 grains per gallon of calcium carbonate.
Undoubtedly, calcium carbonate serves as the standard because it has a molecular weight of approximately 100 (100.089) and an equivalent weight of 50 (50.45). The concentration of the various mineral compounds as calcium carbonate (CaCO_{3}) in a water supply can readily be determined upon analysis of the water. The concentrations of each of the minerals is divided by the equivalent weight of the compound and then multiplied by the equivalent weight of CaC0_{3}.
Thus, to determine the equivalent weight of any mineral compound in terms of calcium carbonate, follow this formula to give you the concentration of that mineral as CaC0_{3}:
concentration of mineral |
x |
__equivalent wt of CaCO___{3} |
equivalent wt of mineral |
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