Iron in Water

The short answer

Iron is common in well water, and it is mostly a problem of looks and taste. The Minnesota Department of Health explains that as rain and snowmelt seep through iron-bearing soil and rock, iron dissolves into the water. Once that water meets air, the iron turns to rust and stains plumbing fixtures and laundry.

One number frames most iron results:

• EPA's secondary standard for iron is 0.3 mg/L^[1]. It is a non-enforceable guideline for taste, color and staining, not a health limit. EPA lists a rusty color, sediment, a metallic taste and reddish or orange staining as the effects you can notice above it.

EPA says the contaminants it covers with secondary standards are not considered to present a risk to human health at the standard. The Minnesota Department of Health says iron in water does not usually present a health risk.

A private well has no one checking it for you. Penn State Extension notes that private water systems serving individual homes are not subject to state or federal drinking water standards. Yellow or red water is often a good sign of iron, but MDH says a laboratory can tell you the exact amount, which helps you choose the right treatment. If the lab doesn't detect iron, or finds it below the standard, no treatment is needed based on that result. Our iron water test guide explains who should test, what to order and how to take the sample.

Iron levels and what to do

The table below shows the federal benchmark for iron and what a result above or below it means for your household. The value comes from our versioned benchmark data, which records EPA's figure and the date we last checked it.

How the iron standard works

Iron has no federal legal limit and no health goal. It has a secondary standard only. EPA sets secondary standards as guidelines to help public water systems manage taste, color and odor, and it does not enforce them. Even public water systems test for these contaminants only on a voluntary basis, EPA says.

So a result above the standard is not a health finding. It tells you how likely you are to see stains, sediment and a metallic taste. A result below it means those problems are less likely, and no treatment is needed based on that result. Our guide on how to read your lab report explains the units and terms you will see on it.

Ask the lab for more than iron

MDH says that in addition to iron, it can help to test for hardness, pH, alkalinity and iron bacteria. Those results shape which treatment will work, as the how-to-fix section below explains. Iron and manganese often occur together in groundwater, according to Penn State Extension. Our guide to manganese in water covers that metal, which also has an EPA health advisory.

Health effects of iron in drinking water

Iron is mostly a nuisance. The Minnesota Department of Health says iron in water does not usually present a health risk. Your body needs iron to carry oxygen in the blood, but most iron comes from food, because the body cannot easily absorb iron from water. EPA's secondary standard for iron is set for color, taste and staining, and EPA says contaminants with secondary standards are not considered a risk to human health at that level.

The taste is real. Penn State Extension describes the bitter metallic taste of high iron water as one that can make the water unpleasant to drink for both people and farm animals. MDH adds that iron can change how food and drinks taste.

The caution is about bacteria. MDH says iron may present some concern if harmful bacteria have entered a well. Some harmful organisms need iron to grow, so iron in the water can make harmful bacteria harder to get rid of.

Iron bacteria are a separate issue. MDH says they are not known to cause disease, but they can create conditions where disease-causing organisms may grow, so it advises testing the water for nitrate and coliform bacteria. Our guide to bacteria in well water explains what a coliform result means.

A water test measures iron in your water, not in anyone's body. If you have health concerns, talk to a health professional and bring your lab report.

Iron in well water and iron bacteria

Rock and soil. The main source is natural. MDH explains that water seeping through iron-bearing soil and rock dissolves iron. Penn State Extension says natural iron is more common in deeper wells, where the water has been in contact with rock for longer, and that in Pennsylvania's coal mining regions iron can also come from deep and surface mining.

Pipes and casing. MDH notes that iron can also come from corrosion of an iron or steel well casing or water pipes.

How common it is. The U.S. Geological Survey sampled domestic wells across the country and detected iron in about half of them. Iron was above EPA's secondary standard in 19 percent^[6] of wells. USGS says iron is a common element in most aquifer materials and dissolves into water under certain conditions, such as low dissolved oxygen and low pH.

Three forms of iron. MDH describes three forms, and each one looks different at the tap:

• Clear-water iron (ferrous). The water comes out clear but turns red or brown after standing.
• Red-water iron (ferric). The water is red or yellow when it first comes out of the faucet.
• Organic iron. It is usually yellow or brown but may be colorless. MDH says very shallow wells, or wells affected by surface water, are more likely to have it.

Knowing the form matters because the treatments differ. Penn State Extension says dissolved iron is most common in groundwater with low pH, while iron that is already solid when it leaves the well is more common in higher-pH water or where the water meets oxygen, as in a shallow spring.

Iron bacteria

Iron bacteria can make an iron problem much worse, MDH says. It describes them as small living organisms that occur naturally in soil, shallow groundwater and surface water. They combine iron or manganese with oxygen to form deposits of rust, bacterial cells and a slime that sticks to well pipes, pumps and plumbing fixtures.

How they get into a well. MDH says drilling, repair or service work can introduce iron bacteria into a well or water system. To keep them out, it advises using only disinfected water in the well during that work, keeping the well casing capped and watertight, and disinfecting the well, pump and plumbing after repairs.

How you notice them. MDH lists swampy, sewage or musty odors, colored water with an oil-like sheen, and sticky rusty, yellow, brown or grey slime. A sign is a reason to test, not a diagnosis: MDH says a laboratory test confirms that it is iron bacteria. If your water has turned color, our page on brown well water walks through what each sign points to and the tests that confirm the cause. Treating the well itself is step 4 of the fix below.

When to test and retest for iron

Test for iron when you see the signs. Penn State Extension advises arranging a test if you notice orange-brown stains or a metallic taste, and using an accredited lab for an overall treatment plan. MDH recommends testing for coliform bacteria every year and any time the water changes in taste, odor or appearance, which covers the iron signs too.

Retest in these situations:

• Before you buy treatment. Penn State Extension says the iron level determines the most practical and economical treatment. Confirm a high result with a state-certified lab, and ask for hardness and pH at the same time.
• After work on the well. MDH says iron bacteria can enter a well during drilling, repair or service work.
• After you install treatment. MDH says to test the treated water to make sure the treatment is working.
• If staining or taste comes back. MDH says treatment units that are not properly maintained lose their effectiveness over time.

You can build a test plan that covers iron and the other tests your well needs, and our well water testing guide explains the yearly well check.

How to remove iron from well water

Start with a result from a state-certified lab. What you do next depends on what it shows, and "no treatment needed" is a real outcome.

If iron was not detected, or is below the secondary standard, no treatment is needed based on that result. Keep the report so you can compare future tests.

If a confirmed result is above the standard, the decision is about stains, taste and clogging, not a health limit. If those problems bother you, these steps will help you choose a fix that works.

1. Know your iron and your water

MDH says effective iron treatment depends on the form of iron, the chemistry of the water, and the type of well and water system, and that it is best to work with a water treatment specialist. Penn State Extension says both the concentration and the form of iron decide the options. Bring your lab report, including hardness and pH if you have them.

2. Compare the treatment options

These are the options MDH and Penn State Extension describe. The right one depends on your result.

Penn State Extension also describes polyphosphate addition, which hides iron rather than removing it. It warns that the water still tastes metallic and that too much phosphate can make the water feel slippery and cause diarrhea.

3. Treat the whole house

Because iron affects every use of the water, Penn State Extension says it must be removed from all water entering the home with point-of-entry treatment. MDH describes two types: point-of-use units treat one faucet, and point-of-entry units treat all of the water in your home.

4. Deal with iron bacteria first

If the lab or the signs point to iron bacteria, treat the well as well as the water. MDH says a licensed well contractor usually starts by removing and cleaning the pump and scrubbing the casing, followed by chemical treatment, most often chlorine. Shock chlorination may need repeating. MDH does not usually recommend continuous chlorine injection, because it may hide other bacterial contamination and cause corrosion.

5. Consider another water source

MDH says other options may include a different water source that is low in iron, such as a public water system, or a new well. It warns that the iron level of a new well is hard to predict, and that shallower wells usually have less iron but may be more prone to nitrate or chemical contamination.

6. Buy carefully, then retest

MDH advises choosing a unit certified by NSF, UL or the Water Quality Association for the contaminant you want removed, where a certification exists, and checking that a contractor is licensed. Penn State Extension suggests comparing dealers, understanding the maintenance, and getting a written warranty.

After installation, retest the treated water with a certified lab. MDH says every treatment unit needs regular maintenance, such as backwashing or changing filters, and that an unmaintained unit can make water quality worse.