Iron and manganese

Their effects and treatment in drinking water

What is iron and manganese?
Iron is a silvery-gray, lustrous metal that makes up about 5 percent of the earth’s crust. Manganese is a gray-white metal that can resemble iron in appearance. Manganese comprises about 0.1 percent of the earth’s crust.
How does iron and manganese get into my well water?
Both these metals commonly get into groundwater as a naturally occurring substance from area rock and soil. In a 2009 study of principal aquifers across the country, the U.S. Geological Survey found iron and manganese in about half the wells sampled.
What kind of problems do iron and manganese cause?
Manganese is an essential nutrient at low doses. Adverse health effects can be caused by over-exposure, with recent studies indicating a possible link to cancer. Children exposed to high concentrations of manganese in groundwater-supplied drinking water performed worse on tests of intellectual functioning than children with lower exposures, according to 2010 research.

Nevertheless, the U.S. Environmental Protection Agency has not established a Maximum Contaminant Level for iron and manganese as a human health risk. Rather, the agency has established a Secondary Maximum Contaminant Level (SMCL) for these metals. For iron, the SMCL is 300 micrograms per liter, which is the same as 300 parts per billion. For manganese, the SMCL is 50 micrograms per liter, the same as 50 parts per billion.

At the SMCL level or above, iron can cause an unpleasant metallic taste. Elevated levels of iron in drinking water also can cause a rusty color that can stain laundry, toilet bowls, sinks, and other surfaces in contact with the water.

Manganese levels at the SMCL also can produce unpleasant tastes and cause black staining. Discolored water is one of the most frequent consumer complaints about drinking water.

Options for addressing problematic levels of iron and manganese
There are three basic options for addressing iron and manganese problems: 1. Explore with a qualified water well system professional the feasibility of retrofitting the well to bypass the metal-producing zones. 2. Construct a new well system that effectively isolates the likely zones of problematic groundwater. 3. Install appropriate water treatment technology.
What type of treatment technologies are effective for iron and manganese?
The two most common methods for reducing iron and manganese levels in drinking water include:

  • Ion exchange
  • Oxidation and filtration.

Ion exchange is a physical/chemical process in which ions are exchanged between a solution phase and solid resin phase. A standard household water softener may effectively remove iron and manganese at concentrations of up to 2 milligrams per liter.

Oxidation and filtration involves oxidation of iron and manganese into forms which can then be filtered out.

Work with a qualified water treatment service provider to determine whether ion exchange technology or oxidation and filtration technology is the best approach to treating problematic iron and manganese in your water.

Each manufacturer may have unique operation and maintenance requirements to assure the long-term treatment performance of its equipment. Before buying a treatment system, well owners should make sure they know these operation and maintenance requirements.

A qualified water treatment service provider or water well system professional can help you determine which technology best meets your needs. Generally, a properly matched ion exchange system can achieve excellent iron and manganese removal with relatively lower equipment costs and operating costs of less than or equal to about $500 a year. Other technologies vary in the degree of effectiveness, equipment costs, and operating costs.

Before buying a water treatment system, well owners should have their test results from a qualified drinking water testing lab. Those results then should be compared to the specifications of the water treatment system under consideration to make sure the system is designed to treat the concentration of perchlorate indicated to acceptable levels.