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Why is my water brown

Why is My Water Brown?


While red or brown is certainly an alarming color to see in your water, don’t panic–it is most likely just iron (and other ferric hydroxides). There are steps you can take to resolve the issue!

We’ve produced this handy guide to answer the following questions:

  • How can you tell if there is iron in your water?
  • What are the effects of iron in tap water?
  • What are the safe levels of iron in drinking water?
  • What type of iron contamination might be in your water?
  • How can you treat iron in drinking water?

How Does Iron Get Into The Water Supply?

Iron–the fourth most abundant mineral in the earth’s crust–is also present in groundwater; unless it is treated or filtered out, it enters the water supply. As pipes and well casings corrode and rust, they can release iron into the water as it flows through.

How Can You Tell If There Is Iron In Your Water?

Unlike some of the stealthier contaminants (like PFAS, pesticides, or radon),  iron contamination often makes its known–irritatingly so. From reddish-brown stains on clothes and fixtures to colored water, iron can cause unpleasant odors and tastes in drinking water or slimy residues and stains on our home appliances.

What Are The Effects Of Iron In Tap Water?

Iron is thankfully not dangerous to human health–it is in fact necessary for us to live and we consume iron in foods such as leafy green vegetables and red meat.

The human body uses iron to carry oxygen in the blood, hence giving blood its rusty red color. While excessive consumption could lead to iron toxicity (the poison is in the dose, as they say), acute iron poisoning is not known to happen from tap water.

What Are The Safe Levels Of Iron In Drinking Water?

The federal drinking water standard for iron is 0.3 milligrams per liter (or 0.3 parts per million).

Brown tap water

How Can You Treat Iron In Drinking Water?

If you are experiencing unpleasant odors and tastes in drinking water or slimy residues and stains on our home appliances, step one is to test your water. Each of our Tap Score Essential, Advanced, and Extended Water Testing packages for city or well water include analysis for iron.  

The form of iron that your water likely contains differs depending on whether your water comes from a (1) water utility or (2) private well.

1. City Water: Ferrous and Ferric Iron

Utility water (from a public water system) is filtered for iron, but treatment plants only reduce iron to levels below the legal concentration limit (0.3 mg/L)–they do not remove iron completely. Over time, small levels of iron can build up in the many miles of pipeline water must travel through before it reaches people’s homes.

Disturbances to the pipes can then knock these mineral deposits loose and into the water stream, including:

  • Main pipeline breaks
  • New construction
  • Heavy irrigation or fire hydrant flushing

The two most common forms of iron in public utility treated water are “ferrous” iron (“clear-water” iron) and “ferric” iron or  (“red-water” iron).

    Ferrous/Clear-water Iron: If your water comes out of the faucet clear but then turns red or brown after sitting.

      Ferric/Red-water Iron: If your water comes out of the faucet red or yellow.

        How Do I Treat Ferrous Or Ferric Iron?

        Ferrous/Clear-water iron: Most commonly treated with a water softener. However, the filter must be changed or backwashed often, because iron will quickly plug it up. 

          Ferric/Red-water iron: Most commonly treated with a manganese greensand filter, but for small concentrations, a sediment filter, carbon filter, or water softener can be used.

            However, we always recommend that you test prior to treating your water. 

            Not served by a water utility? Read on for what to do if your private well is contaminated by iron (or iron-related bacteria).

            2. Well Water: Organic Iron, Tannins, and Bacterial Iron

            Private well water is not usually filtered, so if there is iron in the source water or from your pipes, it will remain there until you filter it.

            Well water can contain clear-water iron or red-water iron, just as public utility water can (see above). It can also contain organic iron and tannins or iron bacteria, both of which are much, much more difficult to remove.

              Organic iron and tannins: Iron reacts with naturally occurring tannins–organic matter from vegetation–to produce black residues. Iron can react with other naturally occurring organic acids to produce organic iron, which is usually yellow and brown. 
                Bacterial iron: Iron  bacteria are naturally occurring organisms that consume iron to survive, and produce a slimy red or brown biofilm in the process. They can enter a well during construction or repair. If left untreated treated they can create an environment where more dangerous organisms can grow. Common signs of iron bacteria include:
                • Tastes and odors: Described as “swampy”, “oily or petroleum”, “cucumber”, “sewage”, “rotten vegetation”, or “musty”. The taste or odor may be more noticeable if the water hasn’t been used for a bit. 
                • Color: yellow, orange, red, or brown stains in sinks or toilets, on laundry, etc.Red slimy deposits: sticky slime that is usually rust colored in toilets or pipes.

                How to test for iron bacteria: We highly encourage testing for bacterial iron if you are concerned, as  these symptoms could be signs of other bacteria. While for chemical contaminants like lead and arsenic, we recommend laboratory tests, you can test for iron-oxidizing bacteria at home.  Learn more here.

                How Do I Treat Organic Iron, Tannins, or Bacterial Iron?

                Organic iron and tannins: Can be treated with chemical oxidation followed by filtration. Water softeners, aeration systems, and iron filters may not work well because organic iron and tannins can slow or prevent iron oxidation. 

                Bacterial iron: Iron bacteria are very difficult to remove, so physical removal, heat, and chemical treatment must be used. The most common treatment is “shock” chlorination, or adding a very strong chlorine solution to a well.



                Iron contamination in water is not dangerous, but can cause undesirable odors, tastes, colors, stains, slimes, and in the case of iron bacteria, can create an environment for other harmful organisms to grow. Because there are so many different kinds of iron in water, you must identify which form you are dealing with to determine which type of removal treatment will work.

                If you have any questions, be sure to email us at! 


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