Iron in Water



The perils of too much iron

Iron is one of the most troublesome elements in water supplies. Making up at least 5 percent of the earth’s crust, iron is one of the earth’s most plentiful resources. Rainwater as it infiltrates the soil and underlying geologic formations dissolves iron, causing it to seep into aquifers that serve as sources of groundwater for wells. Although present in drinking water, iron is seldom found at concentrations greater than 10 milligrams per liter (mg/l) or 10 parts per million. However, as little as 0.3 mg/l can cause water to turn a reddish brown color.

Iron is mainly present in water in two forms: either the soluble ferrous iron or the insoluble ferric iron. Water containing ferrous iron is clear and colorless because the iron is completely dissolved. When exposed to air in the pressure tank or atmosphere, the water turns cloudy and a reddish brown substance begins to form. This sediment is the oxidized or ferric form of iron that will not dissolve in water.

While not hazardous to health, iron is considered a secondary or aesthetic contaminant.

Concentrations of iron as low as 0.5 mg/l will leave reddish brown stains on walls, paving, fixtures and laundry that is very hard to remove. When deposits break loose from water piping, rusty water will flow through the faucet. Within appearance sensitive industries such as facilities management, iron stains can degrade a facility’s image; and within an agricultural environment, iron can cause irrigation equipment and drippers to become clogged, speeding up the replacement cycle.

When iron exists along with certain kinds of bacteria, problems can become even worse. To survive, the bacteria utilize the iron, leaving behind a reddish brown or yellow slime that can clog plumbing and cause an offensive odor. This slime is noticeable in irrigation equipment, tanks and plumbing.

Since iron combines with different naturally occurring organic materials, it may also exist as an organic complex. The combination of naturally occurring organic material and iron can be found in shallow wells and surface water. This type of iron is usually yellow or brown but may be colorless.

Possible treatment solutions should begin with a test for iron concentration. Water Solutions International offers free tests within the Cape Town area and could refer you to suitable service providers in other regions.

The IRONOX water treatment systems are designed to remove excessive iron in water, ranging from as low as 1 mg/l up to 100mg/l. No maintenance, no chemicals are required to operate the standard IRONOX™ treatment system. The IRONOX™ systems cater for water volumes ranging between 10m3/day and 172m3/day, ideal for domestic, commercial and small scale industrial and agricultural use. Custom designed systems can be developed for higher volumes.