Why is my tap water brown?

Start here: is it the hot tap, the cold tap, or both?

Run each tap on its own before you do anything else. Which taps are affected narrows the cause more than any description of the symptom can.

Hot tap only

Sediment inside the water heater

Brown or rusty water on the hot tap alone means the deposit is in the tank. Sediment and corrosion products settle in a water heater over years and get stirred up by demand, while the cold line stays clear because it bypasses the tank entirely. This is an appliance to service, not a supply to worry about.

Cold tap only

Iron and manganese resuspended in the pipes

Brown water on the cold tap points at the pipe rather than the appliance. Iron and manganese settle inside water mains and service lines as a fine deposit, and any change in flow direction or velocity lifts them back into the water. Nothing was added; something was disturbed.

Hot and cold

A supply-side event

Discoloration at every tap normally follows something that disturbed the system — a main break, hydrant flushing, a pump change, or heavy demand nearby. It typically clears within hours once the disturbed material has passed through. The question worth asking is whether the event that caused it also dropped the pressure.

On a city water supply

Municipal brown water is overwhelmingly a distribution story rather than a treatment story: the deposits sit in the mains between the plant and your street, and anything that changes the flow lifts them. That is why a whole block sees it at once and why it clears without anyone treating anything. EPA's distribution-system guidance describes the deliberate version of this — unidirectional flushing, a planned sequential technique that closes isolation valves to drive higher-velocity flow toward one hydrant precisely so sediment is not spread to other customers — and the accidental version, where conventional flushing or an unplanned break mobilizes sediment instead. The two markers to look for in your utility's reported data are iron and manganese. EPA's secondary standards put iron at 0.3 mg/L, where the effects are rusty color, sediment, metallic taste and reddish or orange staining, and manganese at 0.05 mg/L, where they are black to brown color, black staining and a bitter metallic taste. Both are non-enforceable guidelines that systems are not federally required to monitor, so there may be no number published for your address at all. Manganese carries the one genuine health dimension here: Minnesota's health department advises 100 micrograms per liter or less for infants drinking tap water or formula made with it, and 300 micrograms per liter or less for everyone over one year old. Read those against the 0.05 mg/L staining threshold — 50 micrograms per liter — and the useful conclusion is that you will normally see manganese staining well before it approaches either health figure.

On a private well the causes are different — nothing on this page about mains, treatment plants or utility reporting applies. Start with the private-well symptom guides.

What your own utility reports

Enter your ZIP code to see the utility-reported values behind this symptom, taken from the water quality data your system files with regulators. Where your utility reported nothing, this says so rather than filling the gap with an estimate.

What actually fixes it

Run a cold tap for several minutes and see whether it clears. If it does, no equipment was ever going to help: the material came from the main and has already passed. Report it either way, because EPA's own guidance names customer complaints as a trigger for flushing a section of main — the complaint is how the fix gets scheduled. There is one case that is not merely aesthetic, and it is worth knowing where the line sits. EPA guidance for the systems it directly oversees defines a loss of pressure as distribution-system pressure below 20 psi, on the basis that low pressure can pull water from outside the pipe to the inside through cracks, breaks and joints. The required response there is a Tier 1 public notice with a boil water advisory, held until two consecutive days of clean total coliform samples. So: discoloration on its own is a staining problem, discoloration alongside lost pressure or a notice from your utility is a different situation, and you follow the notice. The part that reliably costs money in either case is laundry — do not wash or run hot water while the water is discolored, because that sets iron stains into fabric and pulls sediment into the water heater.

When it is worth testing

The water has not run clear after flushing the cold tap for several minutes.
Report it to your utility first, because they can sample the main and you cannot. If it turns out to be confined to your building, a certified-lab iron and manganese result on a cold-tap sample identifies which of the two metals is doing the staining, which is what decides whether treatment is even the right category of answer.
You lost water pressure, or your utility has issued a notice for your area.
No test of your own. Follow the utility's notice and wait for the all-clear. EPA guidance treats pressure below 20 psi as a loss-of-pressure event, requires a Tier 1 public notice with a boil water advisory, and holds it until two consecutive days of safe total coliform samples — that sequence is the utility's to run, and a home sample taken mid-event tells you nothing useful.
Brown water keeps coming back at the same address, and there is an infant in the house.
A certified-lab manganese result taken while the water is discolored, read against Minnesota's health guidance of 100 micrograms per liter or less for infants drinking tap water or formula made with it, and 300 micrograms per liter for everyone over one year. Pair it with your utility's own reported values so a household-plumbing source can be told apart from a supply-side one.

Frequently asked questions

Is brown tap water dangerous?

Brown water from a municipal supply is most often iron and manganese sediment lifted out of the mains, which is a staining and aesthetic problem rather than an acute hazard — EPA regulates both as secondary, non-enforceable standards on exactly those grounds. That is not the same as saying ignore it. Discoloration that comes with a loss of pressure is a different situation: EPA guidance treats pressure below 20 psi as a loss-of-pressure event requiring a boil water advisory, because low pressure can draw water into the pipe through cracks and joints. Report the discoloration, and follow any notice your utility issues.

How long does brown tap water last?

When it follows a main break or hydrant flushing it usually clears within a few hours, once the disturbed water has passed through the system. Running a cold tap for several minutes both clears your own service line and tells you whether discolored water is still arriving. Discoloration that returns repeatedly at the same address is worth reporting as a pattern rather than as separate incidents — EPA's guidance describes spot flushing being scheduled at locations with a history of customer complaints, and a pattern is what creates that history.

Is brown water iron or manganese, and does it matter?

It matters, because they stain differently and only one has a health figure attached. EPA's secondary standards describe iron above 0.3 mg/L as producing rusty color, sediment, metallic taste and reddish or orange staining, and manganese above 0.05 mg/L as producing black to brown color, black staining and a bitter metallic taste. Black marks in the toilet cistern point at manganese; orange marks at iron. Manganese also has health guidance behind it — Minnesota's health department sets 100 micrograms per liter for infants on tap water or formula and 300 for everyone over one — while iron at these levels is an aesthetic matter.

Can I do laundry when the water is brown?

Wait. Iron-bearing water sets stains into fabric that are difficult to reverse, and this is the part of an episode of brown water that reliably costs people money. Hold off on laundry and on running hot water until a cold tap runs clear, so you are not drawing sediment into the water heater at the same time. Once the cold water is clear, run the washing machine empty before the first real load.

Other tap water symptoms

Sources

U.S. EPA — Secondary Drinking Water Standards: Guidance for Nuisance Chemicals — retrieved 2026-07-27
Minnesota Department of Health — Manganese in Drinking Water — retrieved 2026-07-27
U.S. EPA — Loss of Pressure in Drinking Water Systems — retrieved 2026-07-27
U.S. EPA — Protecting Water Quality Through Distribution System Flushing — retrieved 2026-07-27

All tap water problems by symptom

By TapWaterData Team