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Iron or "Rust" in Minnesota Well Water

Iron makes up nearly 5% of the earth’s crust, and is found in approximately 90% of Minnesota well water. Although Iron is common, it is rarely found in concentrations greater than 10ppm (parts per million).

Iron, Health and Water Quality

Iron is not considered hazardous to health, and at low levels, Iron is essential for good health because it transports oxygen in your blood.

Iron is considered a secondary or “aesthetic” contaminant. The recommended limit for Iron in water of 0.3ppm, is based on taste and appearance rather than on any detrimental health effect.

When the level of Iron in water exceeds the 0.3ppm limit, you get red, brown, or yellow staining of laundry, glassware, dishes, and household fixtures like bathtubs and sinks. Water with Iron content may also have a metallic taste and an offensive odor. Plumbing, appliances, and fixtures also become restricted and clogged from Iron.

Types of Iron in Water

Iron is generally divided into two main categories: soluble and insoluble.

Soluble Iron, aka Ferrous Iron or “Clear Water Iron”, is the most common form. You can determine if you have “Clear Water Iron” with this simple test: pour a glass of cold clear water and let it stand for a few minutes. If you find reddish-brown particles beginning to appear in the glass and eventually settling to the bottom, you have clear water Iron.

When insoluble Iron, aka Ferric Iron or “Red Water Iron” is poured into a glass, it immediately appears rusty or has a red or yellow color. We find that about 40% of Minnesota’s wells have red water Iron. Insoluble Iron can create serious taste and appearance problems for the water user.

Iron may also exist as an organic complex. A combination of acid and Iron, or organic Iron, can be found in shallow wells and surface water. This is more common in Big Lake, Becker, Ham Lake, and various cities on the northeast side of the Twin Cities. Although this kind of Iron can be colorless, it is usually yellow or brown.

Finally, when Iron exists along with certain kinds of bacteria, problems can become even worse. The bacteria consume Iron to survive and leave a reddish brown or yellow slime that can clog plumbing and cause an offensive odor. You may notice this slime or sludge in your toilet tank when you remove the lid.
Once you determine whether you have “clear water,” “red water,” “organic” or “bacterial” Iron in your water, you can take steps to correct the problem. Keep in mind that no one treatment method will work for every type of Iron problem.

Testing Your Water for Iron

Before you attempt to remove anything that appears to be Iron-related, it is important to have your water tested to determine the extent of your Iron problem. These tests include Iron concentration and type, Iron Bacteria, pH, alkalinity, and Water Hardness.

If you have city water, and experience red water problems, it is important to determine whether the red water is from the public system or your home’s plumbing.

How to Select the Right Iron Treatment Method

As a general rule of thumb, you should have a Qualified Premier Water Technician perform a FREE WATER TEST to measure the level and types of Iron in your water. There may also be additional elements that require different or additional treatment methods to guarantee Iron removal.

When choosing an iron filtration system, make sure you have answers to the following five questions:

  1. What form of iron do I have in my water system?
  2. Will the water treatment unit remove the total iron concentration (determined by the water test) in my water supply? (Total iron refers to both soluble and insoluble iron combined).
  3. Will the iron filter treat the water at the flow rate required for my family?
  4. Are there additional measures that need to be used to make this method effectively remove iron? (For example, pH may need to be adjusted before beginning a particular treatment).
  5. Can the system be adequately backwashed (cleaned) with my current well pump?

Four Examples of Common Iron Problems

Example 1 – Soluble, Dissolved, Clear Water, Ferrous Iron Drawn tap water is clear and colorless. When allowed to stand, reddish brown particles appear and settle to bottom.
Efficient Treatment Methods for Ferrous/Clear Water Iron

  • Aeration/filtration
  • Catalytic filtration
  • Chlorination/filtration
  • Ion Exchange water softener – at low levels
  • Manganese greensand

Example 2 – Insoluble, Red Water, Oxidized, Ferric Iron Water appears rusty, or has a red or yellow color. Particles settle when the water is allowed to stand.

Efficient Treatment Methods for Ferric/Red Water/Oxidized Iron

  • Aeration/filtration
  • Catalytic filtration
  • Chlorination/filtration
  • Manganese greensand

Example 3 – Iron Bacteria, Creno-thrix, Leptothrix, Gallionella Water tank, toilet tank, or plumbing have reddish brown or yellow gelatinous slime or sludge buildup. Water may have a foul odor, or an iridescent sheen.

Efficient Treatment Methods for Bacterial Iron

  • Chlorination/filtration
  • Manganese greensand

Example 4 – Organic Iron, Hemme Iron Water has a high color content (yellow or brown), although it may be colorless. Water source is usually from a shallow well, or surface water.

Efficient Treatment Methods for Organic/Hemme Iron

  • Chlorination/filtration
  • Manganese greensand
  • Tannin Removal followed by Aeration/Filtration

Common Iron or “Rust” Treatment Methods

Aeration + Filtration: Introducing oxygen to the water source to convert soluble iron to its insoluble form.  Examples include the Iron Curtain Filter System.

Ozonation + Filtration: A specialized form of aeration using ozone to convert soluble iron. Examples include the Iron Curtain Storm.

Chlorination + Filtration: Chemical oxidizer used to convert soluble iron to an insoluble, filterable form.

Catalytic Filtration: A granular filter medium that enhances the reaction between oxygen and iron and then filters the insoluble iron. Examples include Greensand Plus and Pyrolox.

Mechanical Filtration: Media used to entrap and screen out oxidized particles of iron. Usually requires backwashing to remove accumulated iron.

Ion Exchange Water Softener: Removal of soluble iron by ion exchange. Acceptable ions (such as sodium or potassium) are exchanged for soluble iron.
Sequestering (NOT RECOMMENDED): Chemical agents are added to water to keep metals like iron in solution to prevent rust stains.

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