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Understanding the Water Test Results
Laboratory reports may be difficult to understand. Most companies send a cover letter explaining the report in nontechnical terms and the actual analysis sheet. Call the testing laboratory if you need help with interpretation. Here are items and terms commonly used in laboratory reports.
MCL is the abbreviation for Maximum Contaminant Level. This is defined as acceptable levels as recommended by the U.S. Environmental Protection Agency.
Detection Level is the level at which the laboratory's equipment and procedures were able to produce results within normal acceptable limits of accuracy.
Level Detected is the amount found in your water and may be reported in parts per million (ppm), milligrams per liter (mg/l), parts per billion (ppb) or other appropriate units.
Hardness is the term applied to water containing calcium or magnesium salts. However, the laboratory report usually lists hardness as equivalent calcium carbonate (CaCO3). The results will be reported in parts per million or grains per gallon (one grain per gallon is equivalent to 17.1 ppm).
Hard water, when heated, develops hard scale on pipes, cooking utensils and other metal objects. The life and efficiency of heating equipment are decreased by the production of the hard scale on heating coils or elements. Hard water causes soaps to curd in the water rather than make lather. Minimal problems are usually experienced as long as the hardness value is less than 100 parts per million (5.8 grains per gallon).
Dissolved Gases usually are carbon dioxide (CO2) and hydrogen sulfide (H2S). The concentration of these gases usually is not reported. However, objectionable taste and odor and high acidity may indicate their presence.
Carbon dioxide results primarily from decaying organic matter in water-bearing soils. It accelerates corrosion of iron, brass, copper and aluminum, causing rust-colored stains from copper piping. Hydrogen sulfide comes from a sulfur source, usually accompanies iron in water, and releases a rotten-egg odor. Hydrogen sulfide corrodes iron, brass and copper and causes black stains. Metallic taste often results from the corrosion of plumbing.
Acidity - Normally the pH of the water is 6.5 to 8.0. Water with a pH of less than 7 becomes increasingly acidic. Acid water dissolves metal, shortens the life of plumbing, discolors water, clogs pipes and develops stains on fixtures. Water systems of all plastic piping with glass-lined tanks are less affected by acidity than metal plumbing.
Iron - The level of iron in the water analysis report should be less than 0.3 parts per million (milligrams per liter) for a domestic well. Iron from a well usually is dissolved ferrous bicarbonate, which is colorless. However, exposure to air or heating changes this compound to ferric hydroxide, which gives water a red or rusty appearance, stains fixtures and develops a metallic taste in water.
Iron also can be accompanied by iron bacteria. These bacteria multiply in the water and consume iron while producing a rust-colored slime that coats the interior surfaces of the plumbing. Total disinfection with regularly repeated treatment might be necessary to control the bacteria.
Turbidity (cloudy water) levels should be less than 5 units to be considered safe. Take special care to determine the reason for the turbidity, because this can be a symptom of a more serious water contamination problem.
Turbidity can be caused by suspended solids such as mud, algae, iron or other materials. Increases in turbidity after rainfall can indicate surface or other introduced pollution.
Color, Palatability or Odor usually results from some of the already mentioned conditions. Correction of any existing conditions most likely improves color, taste and odor.
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