Why Is My Well Water Brown?

What causes brown well water

Why is my well water brown? In most wells the answer is a metal from the rock around the well: iron, sometimes with manganese. Penn State Extension says both often occur together in groundwater, with manganese usually at much lower concentrations than iron. Brown well water can also come from iron bacteria or from sediment. The color alone cannot tell you which, or how much.

These are the causes the primary sources name:

• Iron. The Minnesota Department of Health (MDH) explains that as rain and snowmelt seep through iron-bearing soil and rock, iron dissolves into the water, and that iron can also come from a corroding iron or steel well casing or water pipes. EPA lists a rusty color, sediment, a metallic taste and reddish or orange staining as the signs of iron. Penn State Extension found excessive iron in 17 percent^[4] of the private water supplies it sampled in Pennsylvania.
• Manganese. EPA lists a black to brown color, black staining and a bitter metallic taste. MDH says manganese can leave a brownish-black or black stain on toilets, showers, tubs and sinks.
• Iron bacteria. MDH describes them as small organisms that occur naturally in soil, shallow groundwater and surface water. They combine iron or manganese with oxygen to form rust deposits and a slime that sticks to well pipes, pumps and fixtures, and they can cause yellow, orange, red or brown stains and colored water.
• Sediment. Penn State Extension links turbid, cloudy or dirty water to silt, sediment and clay from runoff, nearby earth disturbance or drilling. It says the same look can come from iron or manganese that has oxidized in the water.

The color often appears only after the water leaves the tap. Penn State Extension says water from a well with high iron or manganese may look colorless at first, then form orange-brown (iron) or black (manganese) stains or particles once it meets oxygen.

Check the timing, the stains and for iron bacteria

Before you order a test, note when the color shows up and what it leaves behind. It narrows down the cause.

Signs of iron bacteria

MDH lists three kinds of sign. Colors: yellow, orange, red or brown stains and colored water, and a rainbow-colored, oil-like sheen. Deposits: sticky rusty, yellow, brown or grey slime, and feathery growths, especially in standing water. Odors: swampy, oily, cucumber, sewage, rotten vegetation or musty smells, which may be more noticeable after the water has not been used for a while. Penn State Extension adds an orange or opaque gelatinous film coating toilets and sinks. MDH says drilling, repair or service work can bring iron bacteria into a well, so a change after work on the well is a clue. Our page on iron bacteria and iron in well water covers them in more detail.

A sign is a reason to test, not a diagnosis. MDH recommends testing for coliform bacteria every year and any time the water changes in taste, odor or appearance.

The tests that confirm it

Penn State Extension says stains and a metallic taste often make iron and manganese obvious, but that a test is still needed to find the exact concentration of each, because the concentration decides the most practical treatment. Order an iron water test and a manganese water test together. MDH says it can also help to test for hardness, pH, alkalinity and iron bacteria, and that a laboratory test confirms iron bacteria.

Is brown well water harmful? Iron and manganese benchmarks

Iron: a nuisance benchmark. EPA's secondary standard for iron is 0.3 mg/L^[6]. EPA does not enforce its secondary standards. They are guidelines for taste, color and odor, and EPA says these contaminants are not considered to present a risk to human health at the standard. MDH says iron in water does not usually present a health risk. Its one caution: some harmful organisms need iron to grow, so iron can make harmful bacteria harder to get rid of if they have entered a well.

Manganese: two benchmarks. EPA's secondary standard for manganese is 0.05 mg/L^[6], set for color, staining and taste. Manganese also has an EPA lifetime health advisory of 0.3 mg/L^[7]. Penn State Extension says the advisory is non-enforceable and was created over concerns about neurological effects from regularly drinking water above it. MDH says you may want to test for manganese especially if infants drink your tap water. A brown or black stain cannot tell you which side of the advisory your water is on. Only a lab result can.

Iron bacteria: a reason to test for bacteria. MDH says iron bacteria are not known to cause disease, but they can create conditions where other disease-causing organisms may grow. MDH advises testing the water for nitrate and coliform bacteria, and making sure the well is properly constructed, located and maintained. Start with a water bacteria test and a nitrate water test.

No standard applies to your well. Penn State Extension notes that private water systems serving individual homes are not subject to state or federal drinking water standards, so these benchmarks are guidelines for managing your own well. And clear water is not a clean result: MDH says you cannot taste, see or smell most contaminants. A water test measures your water, not your health; if you feel unwell, talk to a health professional.

How to fix brown well water once a test confirms the cause

Fix the cause the test confirms, not the color. Penn State Extension says results from a state-accredited laboratory should be used to confirm causes and severity, and that testing may turn up other problems the obvious symptom hides. Our guide to how to read your lab report explains the numbers.

"No treatment needed" is a valid outcome. If iron and manganese are below EPA's secondary standards, no treatment is needed based on that result. If a result is above a secondary standard but manganese is below the health advisory, the decision is about stains and taste, not a health limit.

Iron and manganese: treat all the water entering the home. Penn State Extension says that because iron and manganese affect every use of the water, they must be removed with point-of-entry treatment, and that the form and concentration of the metals decide which process works. The options it describes:

• A water softener, for low to moderate iron and low manganese, if the manufacturer recommends it.
• An oxidizing filter, such as manganese greensand, for higher concentrations.
• Oxidation followed by filtration, for the highest combined levels.

MDH says effective iron treatment also depends on the chemistry of the water and the type of well, and that it is best to work with a water treatment specialist. Bring your lab report, with hardness and pH if you have them.

Iron bacteria: treat the well, not only the water. MDH says eliminating iron bacteria can be difficult and expensive, and that treatment may be only partly effective, so it suggests a licensed well contractor or water treatment professional. The contractor usually starts by removing and cleaning the pump and scrubbing the casing, followed by chemical treatment, most often chlorine, which may need repeating. MDH does not usually recommend continuous chlorine injection, because it may hide other bacterial contamination and cause corrosion problems.

Sediment: filtration. For turbid or dirty water, Penn State Extension describes a cartridge filter for less severe cases and multi-level media filtration for more severe ones.

Before you buy, Penn State Extension advises comparing units and prices from several dealers, understanding each unit's maintenance, and getting a written warranty.

• Iron in Water
• Manganese in Water