Iron Water Test

Who should test for iron

The U.S. Geological Survey detected iron in about half of the domestic wells it sampled across the country, and found it above EPA's secondary standard in 19 percent^[5] of them. In Pennsylvania, a Penn State survey found excessive iron in 17 percent^[4] of the private water supplies it sampled.

If you have a private well, the test is up to you. Penn State Extension reminds well owners that private water systems serving individual homes are not subject to state or federal drinking water standards. Even public water systems test for iron only on a voluntary basis, EPA says, because iron has a secondary standard rather than a legal limit.

Test when you see the signs. Penn State Extension says that if you notice orange-brown stains or a metallic taste, you should arrange to have your water tested for iron. The Minnesota Department of Health (MDH) lists the signs to look for:

• Yellow, red or brown stains on dishes, laundry and plumbing fixtures.
• A metallic taste that changes how food and drinks taste.
• A rainbow sheen on tea and coffee in bright light, and potatoes that turn black.
• Wells, pumps, sprinklers and dishwashers that clog over time.

Water with iron does not always look rusty at first. MDH describes clear-water iron, which comes out of the faucet clear and turns red or brown after standing.

Test before you buy treatment. Penn State Extension says the iron level determines the most practical and economical treatment, so a measured result comes before any equipment decision. A test is also how you find out that no treatment is needed.

Iron and bacteria. MDH says iron can make harmful bacteria harder to get rid of if they enter a well, because some harmful organisms need iron to grow. It recommends testing for coliform bacteria every year and any time the water changes in taste, odor or appearance. Our guide to bacteria in well water explains that test.

To see iron alongside the other tests your home needs, you can build a test plan, or read our well water testing guide for the yearly well check.

Certified lab or home kit

A lab gives you the exact amount. MDH says yellow or red water is often a good indication that iron is present, but a laboratory can tell you the exact amount of iron, which is useful in deciding on the best type of treatment. MDH recommends an accredited laboratory: contact one to get sample containers and instructions, or ask your county environmental or public health office whether it offers well testing. CDC tells well owners that local or state health departments should have a list of state-certified laboratories. Our directory of certified water testing labs lists state-certified labs in the states we cover, and our guide to well water testing cost shows verified lab prices.

A home kit gives you a rough read. A strip or color chart you read yourself is not a measured concentration from a certified lab, and you can't compare it with EPA's standard in the same way. Choose a certified lab when:

• You want a number to compare with EPA's secondary standard.
• You are about to spend money on a softener or iron filter, or you want to check that one is working.
• You are buying or selling a home with a well and need a result you can show someone else.
• A home kit showed iron, and you want to know how much.

Ferrous vs ferric iron: what to order

Iron in well water comes in more than one form. MDH describes ferrous or "clear-water" iron, which comes out of the faucet clear and turns red or brown after standing, and ferric or "red-water" iron, which is red or yellow as soon as it leaves the faucet. A third form, organic iron, is usually yellow or brown. Penn State Extension says it is important to know the form as well as the concentration, and MDH says effective iron treatment depends on the forms present. Here is what to ask for:

• Iron. This is the number to order. The Wisconsin Department of Natural Resources (DNR) frames the treatment question around the total iron concentration a water test determines, which it defines as soluble (ferrous) and insoluble (ferric) iron combined.
• The form, by looking. These sources tell the forms apart by how the water looks, not by a separate lab test. Wisconsin DNR identifies them in a glass of cold water: clear water that forms reddish brown particles as it stands has ferrous iron, while water that looks rusty, red or yellow as soon as it is poured has ferric iron. Penn State Extension adds that dissolved iron is most common in groundwater with low pH. Write what you saw on the sample form.
• Iron bacteria, manganese, hardness, pH and alkalinity. Wisconsin DNR says a complete test of an iron problem should include iron concentration, iron bacteria, manganese, pH, alkalinity and hardness. MDH lists the same extras except manganese, and says a laboratory test confirms iron bacteria. Penn State Extension says iron and manganese often occur together in groundwater, so you may want to add a manganese water test to the same order.

Lab methods

• EPA 200.7
• EPA 200.9
• SM 3120 B
• SM 3111 B
• SM 3113 B

Source: ecfr.gov (source for lab methods) (opens in a new tab)

How to collect an iron sample

Follow the instructions in your lab's kit first, since they are written for that lab's bottle and method. The methods labs use to measure iron are listed under "Certified lab or home kit" above. The steps below explain what most kits ask you to do and why.

1. Decide what you want to know. MDH says iron can come from the rock and soil around a well and also from corrosion of an iron or steel well casing or water pipes. If you have a softener or iron filter, ask the lab whether to sample before it, after it, or both. Sampling before treatment tells you about the well; sampling after it tells you whether the treatment works.
2. Pick the right tap. Use a cold-water tap you drink or cook from, usually the kitchen sink, unless your lab names another one.
3. Remove any attachments. Take off a hose or aerator attachment, unless your kit says otherwise.
4. Run the water the way your lab says. Your kit tells you whether to let the water run before you fill the bottle, and for how long. Follow it exactly, so your result can be compared with later tests.
5. Fill the bottle without rinsing it. If the bottle came with anything inside, don't rinse it out. Fill to the line, cap it tightly, and avoid touching the inside of the cap or bottle.
6. Write down what you saw. Record the date, time and tap, whether the sample was before or after treatment, and whether the water came out clear or already colored.
7. Send it on time. Pack the sample the way your lab asks and send it within the window it gives you.

If you are testing for bacteria at the same time, read every bottle's instructions first and plan your day around the bottle with the shortest window.

Common mistakes to avoid

• Sampling only after a softener when you wanted to know about the well itself.
• Rinsing out a bottle that came with something already inside.
• Sampling from an outdoor spigot or a hose when you wanted to know about your drinking water.
• Leaving out whether the water was clear or rusty when it came out.

What your iron level means

Your lab report gives a number. Here is how to read it against the federal benchmark.

EPA's secondary standard for iron is 0.3 mg/L^[1]. It is a non-enforceable guideline that EPA sets to help public water systems manage taste, color and odor. EPA says the contaminants it covers with secondary standards are not considered to present a risk to human health at the standard. Iron has no federal legal limit and no health goal.

What a result above it means. EPA lists a rusty color, sediment, a metallic taste, and reddish or orange staining as the effects of iron above the standard. MDH says water above that level is usually considered objectionable. It is a finding about stains, taste and clogging, not a health limit.

Health questions. MDH says iron in water does not usually present a health risk, and that most iron in the body comes from food, since the body cannot easily absorb iron from water. If you have health concerns, talk to a health professional and bring your lab report. Our guide to iron in water covers where iron comes from, its three forms and how to remove it after a confirmed result.

Putting your result in context

• No iron detected. No treatment needed based on this result. Keep the report so you can compare future tests.
• Iron detected, below the secondary standard. No treatment needed based on this result. Stains and a metallic taste are less likely at this level.
• At or above the secondary standard. If the stains or taste bother you, confirm the level with a certified lab, ideally with hardness and pH. 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.

Don't decide on treatment from a single home-kit reading. Any treatment choice should start from a confirmed certified-lab result, and a retest of the treated water shows whether it worked.