Iron Filter for Well Water: When You Need One, and What to Do First

Test before you buy an iron filter

Send a sample to a certified lab and ask for iron, manganese, pH, hardness, and hydrogen sulfide. The well water testing guide explains where to send it. The pH decides which media can work. Hardness decides whether a softener belongs in the system, and hydrogen sulfide rules out some media.

The EPA secondary standard for iron is 0.3 mg/L, and the standard for manganese is 0.05 mg/L. Above those levels, the EPA lists rusty or black color, metallic taste, and staining. The EPA does not enforce these standards, so the choice to treat is yours. Source: EPA secondary drinking water standards (updated May 26, 2026). One mg/L is the same as one part per million (ppm).

Which kind of iron do you have?

The Minnesota Department of Health describes three forms of iron in well water, and iron bacteria are a fourth problem. Source: Minnesota Department of Health, Iron in Well Water (updated August 1, 2025).

• Dissolved iron (ferrous or clear-water iron). The water comes out clear and turns red or brown after it stands in a glass.
• Particulate iron (ferric or red-water iron). The water is red or yellow when it leaves the tap. The iron is already a solid, so a filter must catch it.
• Organic iron. The water is yellow or brown, and sometimes clear. The iron is bound to organic matter, often in shallow wells or wells affected by surface water. Softeners and most iron filters do not work well on it.
• Iron bacteria. You see red, brown, or grey slime in the toilet tank, a swampy or musty odor, or an oily sheen. These organisms live in the well and the plumbing and feed on the iron.

The rust stains guide helps you read the stains. A metallic taste usually points to dissolved iron or manganese. Brown or black slime at the aerators points to a colony, and the black slime guide covers that sign.

Iron filter decision table: iron form and level to treatment

Find the row that matches your water and your lab report.

Iron filter types compared

Each filter type has conditions it needs to work. Check the spec sheet for the model you buy, because each maker sets its own limits.

Sizing an iron filter for your well

Most whole-house iron filters clean their media with a backwash. The media maker sets the backwash rate in gallons per minute for each square foot of tank. Your well pump must supply that flow, or the bed does not clean and the filter clogs. Measure your pump flow before you buy. Time how long an open outside spigot takes to fill a 5-gallon bucket, and give that number to the dealer.

Give the dealer your full lab report as well. If your pH is below the limit for the media you want, the dealer can add a neutralizer stage first. Clack, the maker of Birm, names calcite as one option. If your water is also hard, put the iron filter ahead of the softener so the resin sees less oxidized iron.

What an iron filter costs

Septic & Well Pro, Well Water Filtration Cost (updated April 10, 2026) lists these ranges. Get a written quote, because prices change by region and installer.

• An iron and manganese filter costs $1,000 to $3,000 installed. It costs $25 to $75 a year to run, plus new media every 5 to 8 years at $250 to $500.
• A sediment filter costs $200 to $800 installed, plus cartridges.
• An under-sink reverse osmosis unit costs $200 to $600, plus $50 to $150 a year.

When the well needs a cleaning before the filter

Iron bacteria live on the well casing, the pump, the pressure tank, and the pipes. A filter in the basement cannot reach them. The slime they make coats filter media and the softener resin, and pieces of slime break off and plug the bed. The iron bacteria guide explains the signs in detail.

The Minnesota Department of Health says physical removal by a licensed well contractor is usually the first step in a heavily infected well, followed by chemical treatment. For a chlorine treatment, the department says the concentration should be close to, but not greater than, 200 ppm. Source: Minnesota Department of Health. Ohio State Extension says iron bacteria grow back and that the system may need treatment every 6 to 24 months. It suggests you check the toilet tank for slime to set the schedule. Source: Ohio State University Extension, Iron in Drinking Water, AEX-323 (May 21, 2021).

Before any well treatment, ask the maker of each filter what to do. The University of Nebraska-Lincoln Extension says softeners, sand filters, and iron removal filters can often be backwashed with a strong chlorine solution. It also says carbon and reverse osmosis filters should generally come out of the line until the chlorine is flushed. Source: University of Nebraska-Lincoln Extension, Shock Chlorination, G1761 (2007). The quick answer on whether treating a well kills iron bacteria covers what to expect from a treatment.

The Save My Well kit contains Selectrocide chlorine dioxide pouches and two bacteria tests. The product's label lists potable water systems among its uses, and you follow that label; the second bacteria test, 7 to 14 days after, shows the result. A filter then handles the dissolved iron that comes in with the groundwater. Retest for iron after the cleaning, and use the table above to pick that filter.