Interpreting Water Analysis Results: A Comprehensive Guide

Understanding Water Analysis Reports

Analysis and Interpretation of Water Sample No. 1

Carefully review the detailed analysis provided below. Afterward, consider the proposed solutions and the rationale behind them. It’s possible that alternative effective solutions may 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 CaC08 equivalent except pH and iron.*

Analysis Interpretation

The water sample analyzed falls into the category of very hard water, according to the Water Quality Association’s classifications, with a total hardness of 15.8gpg. The total cations amount to 16.4gpg, with sodium contributing 0.6gpg to the difference between total anions and total hardness. The iron content is minimal and would not cause any laundry staining.

Proposed Solutions for Water Treatment

A viable solution for treating this hard water would be to install an ion exchange softener with the appropriate capacity on both hot and cold water lines. It’s advisable to bypass outdoor sillcocks and, if feasible, toilets, as the iron content is too low to cause significant staining.

The necessary capacity of the unit will depend on the household size and the number of water-using appliances. The choice between manual, semi-automatic, or fully automatic models is subjective and based on the buyer’s preference.

Understanding the Units of Measure

Water Analysis Example No. 1 lists iron in parts per million (ppm), while all other hardness minerals are reported in grains per gallon (gpg). This is done for convenience in reporting mineral concentrations, which vary widely in water.

Units of Measure in Water Analysis

Four basic units of measure are used in water analysis: 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 convert ppm to gpg, divide the ppm value by 17.1. For example, milligrams per liter or parts per million equals grains per gallon divided by 17.1.

Caution with Units

It’s important to understand that parts per million refers to one part in a million parts. For instance, 1 ppm can be translated as one ounce in a million ounces of water or one pound in a million pounds of water. However, it’s incorrect to interpret 1 ppm as one pound in a million gallons of water without conversion, as pounds and gallons are not equivalent units.

Expressing Hardness

The point-of-use water conditioning industry typically expresses hardness in gpg to avoid large numbers, except for trace substances, which are reported in mg/1. The minerals assessed in these analyses are expressed in hypothetical combinations as calcium carbonate (CaC03).

Calculating Hardness Mineral Concentrations

To calculate the concentrations of various hardness mineral compounds, the ion concentrations must be expressed in equivalent units, allowing for direct addition and subtraction in analysis. This is similar to converting 113 and 114 to 4112 and 3112 for easier arithmetic operations.

Chemical Equivalence in Water Minerals

If water contains 10 grains per gallon of minerals as CaC03, these may include calcium or magnesium carbonates, bicarbonates, sulfates, or chlorides, or a combination of these compounds. The combined concentration of these hypothetical combinations is chemically equivalent to 10 grains per gallon of calcium carbonate.

Calcium Carbonate as a Standard

Calcium carbonate is the standard due to its molecular weight of approximately 100 (100.089) and equivalent weight of 50 (50.45). The concentration of mineral compounds as CaC03 in a water supply can be determined upon analysis. The concentrations of each mineral are divided by the compound’s equivalent weight and multiplied by the equivalent weight of CaC03.

To calculate the equivalent weight of any mineral compound in terms of CaC03, use the formula: concentration of mineral × equivalent weight of CaC03 / equivalent weight of mineral.

Final Thoughts on Water Analysis

In conclusion, interpreting water analysis reports requires a careful examination of the provided data and an understanding of the units of measure used. By considering the proposed solutions and the reasons behind them, you can make informed decisions about water treatment options. Remember, the goal is to ensure the water quality meets the necessary standards for safe consumption and use.