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How do I test for Hardness?

Contact your local health department for a list of state-certified laboratories that can test the hardness level of your water. Less expensive home tests can be ordered through us. Click HERE.

The following classifications are used to measure hardness in water: soft 0 - 17.1 parts per million (ppm); slightly hard 17.1 – 60 ppm; moderately hard 60 - 120 ppm; hard 120 -180 ppm; and very hard 180 or more ppm.  


Forms of Iron

Iron can occur in water in a number of different forms. The type of iron present is important when considering water treatment. Water that comes out of the faucet clear, but turns red or brown after standing is “ferrous” iron, commonly referred to as “ clear-water ” iron. Water which is red or yellow when first drawn is “ferric” iron, often referred to as “ red- water ” iron. Iron can form compounds with naturally occurring acids, and exist as “ organic ” iron. Organic iron is usually yellow or brown, but may be colorless. Water containing   iron bacteria   is said to contain “ bacterial ” iron.



Yellow or red colored water is often a good indication that iron is present. However, a testing laboratory can determine the exact amount of iron, which can be useful in determining the best type of treatment. In addition to testing for iron, it can be of value to also test for hardness, pH, alkalinity, and iron bacteria. County health departments may offer some of these tests. Private testing laboratories   can be contacted about their services and fees. Most advertise in the phone book under “Laboratories-Testing.”

The amount of a dissolved material in water is usually reported as the number of milligrams per liter (mg/L). This is the weight of material in 1 liter (approximately 1 quart) of water. A milligram per liter is approximately equal to 1 part per million (ppm). Iron in amounts above 0.3 mg/L is usually considered objectionable. Iron levels are usually less than 10 mg/L.


Water Treatment

Treatment of water containing iron depends on the form(s) of the iron present, the chemistry of the water, and the type of well and water system.

Clear-water iron   is most commonly removed with a water softener. Manufacturers report that some units are capable of removing up to 10 mg/L, however 2 to 5 mg/L is a more common limit. A water softener is actually designed to remove hardness minerals like calcium and magnesium. Iron will plug the softener, and must be periodically removed from the softener resin by backwashing. Also, if the water hardness is low and the iron content high, or if the water system allows contact with air, such as occurs in an air-charged “galvanized” pressure tank, a softener will not work well. Ion exchange water softeners add sodium to the water which may be a concern for persons on a sodium restricted diet.

Red-water iron   can be removed in small quantities by a sediment filter, carbon filter, or water softener, but the treatment system will very quickly plug up. A more common treatment for   red-water iron   and   clear-water iron   in concentrations up to 10 or 15 mg/L is a manganese greensand filter, often referred to as an “iron filter.” Aeration (injecting air) or chemical oxidation (usually adding chlorine in the form of calcium or sodium hypochlorite) followed by filtration are options if iron levels exceed 10 mg/L.

Organic iron and tannins   present special water treatment challenges. Tannins   are natural organics produced by vegetation which stain water a tea-color. In fact, the tannins in coffee or tea produce the brown color. When tea or coffee is made with water containing iron, the tannins react with the iron forming a black residue.   Organic iron   is a compound formed from an organic acid and iron. Organic iron and tannins can occur in very shallow wells, or wells being affected by surface water. Organic iron and tannins can slow or prevent iron oxidation, so water softeners, aeration systems, and iron filters may not work well. Chemical oxidation followed by filtration may be an option.


Well Treatment

Iron bacteria   are organisms that consume iron to survive and, in the process, produce deposits of iron, and a red or brown slime called a “biofilm.” The organisms are not harmful to humans, but can make an iron problem much worse. The organisms naturally occur in shallow soils and groundwater, and they may be introduced into a well or water system when it is constructed or repaired.

Treatment options for elimination or reduction of iron bacteria include physical removal, heat, and chemical treatment. The most common treatment is “shock” chlorination of the well and water system. See   Iron Bacteria in Well Water . Remember, iron bacteria need iron to survive. Eliminating the bacteria will not eliminate the iron - both   well   treatment for the bacteria, and   water   treatment for the iron will be needed.

Most companies recommend a limit of 0.3 parts per million of iron in drinking water, but this is based on the taste and appearance of the water rather than any health hazards. At this level a mechanical water softener can remove iron along with other water hardening minerals.



Iron levels between 3 and 10 parts per million and over 10 parts per million are considered moderate and high, respectively. These levels may result in staining of laundry and household fixtures such as sinks and bathtubs, but water can be treated with an oxidizing filter or chlorination/filtration system before it enters the lines.

Total Dissolved Solids in Drinking Water

In terms of Total Dissolved Solids (TDS), in the U.S., the Environmental Protection Agency (EPA) advises against consuming water containing more than 500mg/liter, otherwise known as 500 parts per million (ppm) of TDS, although many health specialists believe that ideal drinking water should be under 50 ppm or lower. The average tap water in America contains approximately 350 ppm of TDS although it is not uncommon for municipal or local water supplies to exceed this. If TDS levels exceed 1000mg/L, however, it is generally considered harmful to human health and should not be consumed.

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