Brown well water looks alarming. It’s usually not an emergency, but it is a signal that something specific is happening in your well or aquifer. The fix depends entirely on what that something is, so diagnosing before buying equipment saves you a significant amount of money.
There are three causes that account for almost all cases of brown well water.
The Three Causes
Iron oxidation is the most common. Water comes out of the tap clear. You fill a glass. After 30-60 seconds, it starts turning orange or rust brown. That’s ferrous iron, which is dissolved iron that oxidizes on contact with air. The iron was invisible in solution and became visible when it hit oxygen.
The fix is an iron filter matched to your iron level and form. Learn more on the iron in well water page.
Sediment produces different-looking water. It comes out visibly brown or reddish from the tap, sometimes with particles you can see floating. It may look cloudier than orange. Sediment issues often start suddenly after heavy rain, nearby drilling, a drop in water table, or pump disturbance that kicks up material from the well bottom.
A sediment filter addresses the immediate appearance, but you also need to figure out why the sediment is there. Sudden sediment can signal surface water intrusion, which brings bacteria risk with it.
Tannins produce a yellow-brown or tea-colored tint. They’re most common in surface wells and shallow wells in swampy or wooded areas. Tannins are organic acids that leach from decomposing vegetation into the water table. They don’t have a metallic smell. They’re not a health risk at typical concentrations, but they stain laundry and taste earthy.
The fix is activated carbon or anion exchange resin.
How to Tell the Difference at Home
You can narrow down the cause before spending money on a lab test.
Fill a clear glass and let it sit for 5 minutes. If it stays brown with particles visible: sediment. If it runs clear from the tap and turns orange in the glass: dissolved iron oxidizing. If it’s consistently yellow-brown and clear, without changing after a few minutes: tannins.
Smell it. Iron bacteria (a different issue, see below) often produces a slight sulfur or musty smell alongside the discoloration. Tannins smell earthy, like wet leaves. Sediment is usually odorless.
Time it. Did the brown water start suddenly after a heavy rain or power outage? More likely sediment. Has it always been this way since you moved in? More likely iron or tannins.
Get the Lab Test Before Buying Equipment
Home observation gets you close. A certified lab test gets you certain.
Request a panel that includes total iron, ferrous iron, ferric iron, turbidity, and TOC (total organic carbon, which catches tannins). This panel typically costs $60-120. That’s much less than buying the wrong filter.
The well water testing guide covers how to find a certified lab in your area.
Iron Bacteria: The Case That Looks Like Both
Iron bacteria deserve their own mention because they’re often mistaken for regular iron problems.
Look in the toilet tank. Orange-brown slime on the inside walls, a reddish coating under the toilet lid, or a slimy clog in your filter housing are signs of iron bacteria. These aren’t just dissolved iron. They’re microorganisms that metabolize iron and create a biofilm.
Treatment is different: shock chlorination to break the biofilm first, then filtration. Running an iron filter on iron bacteria without addressing the biofilm is ineffective. The bacteria colonize the filter media.
When to Be More Concerned
Brown water from iron, tannins, or minor sediment is an aesthetic issue in most cases. But if your brown water started after a chemical spill, a nearby industrial event, or if multiple wells in your immediate neighborhood changed at the same time, call your county health department. That pattern points to something beyond individual well variation.
A sudden change in water color, especially accompanied by new smell or taste, always warrants a bacteria test before you drink it while investigating the cause further.
What to Do Right Now
Fill a clear glass. Set a timer for 5 minutes. Note whether the water is brown from the start or turns orange after sitting. Note whether there are visible particles. Smell it.
That observation narrows you to one of three causes. Then get a lab test to confirm before buying any equipment. The how to remove iron from well water guide covers treatment once you know what you’re dealing with, and the best iron filters review covers equipment options if iron is your issue.