What causes brown water from the tap?

Brown tap water is almost always iron, rust, or disturbed sediment. In municipal water, it usually means a nearby main break or routine pipe flushing stirred up scale inside old pipes. In well water, it's typically dissolved ferrous iron that oxidizes when it hits air. Brown from the hot tap only points to sediment or corrosion inside your water heater.

Is brown tap water safe to drink?

It depends on the source. Brown municipal water after a main break is generally safe once it runs clear, but your utility will usually issue guidance. Brown well water from iron is not a health hazard at typical concentrations, though you should get it tested to confirm iron is the only issue. Brown water you can't explain should not be consumed until you know what's causing it.

Why is only my hot water brown?

If only the hot tap runs brown, the problem is almost always your water heater, not your well or municipal supply. Sediment accumulates at the bottom of the tank over time. Old anode rods corrode. The tank lining can rust if the anode rod has fully depleted. Flushing the tank is the first step. If the water runs clear after a good flush, sediment was the culprit.

How do I fix brown well water?

Get a certified lab test first. Brown well water is usually iron, but it could also be manganese or sediment from a cracked casing. The right treatment depends on the form of iron present. Dissolved ferrous iron needs an oxidizing filter. Particulate ferric iron can often be addressed with sediment filtration. Iron bacteria need shock chlorination before any filter will work.

When should I call my water utility about brown water?

Call immediately if the brown water appeared suddenly, if your neighbors are also affected, or if a utility crew has been working on mains in your area recently. This usually indicates a main break or emergency flushing that disturbed pipe scale. Your utility may issue a boil water notice. Don't wait to see if it clears on its own when the cause is unknown.

Brown Water from Your Tap: What Causes It and What to Do

Brown water is jarring. But it almost always has a straightforward cause, and the source of the problem determines the fix.

The three most common culprits are iron, pipe rust, and sediment. The tricky part is figuring out which one you have, because treating the wrong one wastes money and time.

Scenario 1: Municipal Water That Suddenly Turns Brown

If your tap water is normally clear and turns brown without warning, call your utility first.

Brown municipal water usually means a main break, pressure surge, or scheduled pipe flushing disturbed scale and rust that had built up on the inside of aging iron water mains. That rust gets shaken loose and carried to nearby homes before it settles or flushes out.

This is a municipal infrastructure problem, not a problem with your home’s plumbing. Your utility will typically know about it already. Run cold water for a few minutes. If it clears up within 5 to 10 minutes of flushing, that’s a strong sign it was a temporary disturbance.

If it doesn’t clear, or if your utility has issued a boil water advisory, follow their guidance. Don’t drink it until you know it’s resolved.

Scenario 2: Well Water That’s Always Slightly Brown

This pattern points almost directly at dissolved iron.

Groundwater picks up iron as it moves through iron-bearing rock and soil. Ferrous iron is dissolved in the water, which means the water may look clear when it first comes out of the tap. But when it sits in a glass or hits a white sink basin, oxygen reacts with the dissolved iron and forms rust-colored particles. That’s why your sink has orange stains and your laundry comes out dingy.

The higher the iron concentration, the faster the water turns and the darker the staining.

Well water iron that’s “always been there” is not an emergency. But you should still get it tested before buying any equipment. The form of iron matters. Dissolved ferrous iron, particulate ferric iron, and iron bacteria each require different treatment approaches. A lab test that distinguishes between them costs $50 to $150 and can save you from buying a system that won’t work for your specific problem.

Read more about the three iron types and what to do about them at iron in well water. For a full walkthrough of how to collect and submit a well water sample, see the well water testing guide.

Scenario 3: Only the Hot Water Is Brown

This is one of the most misdiagnosed water problems homeowners face.

If your cold water runs clear and only the hot tap produces brown or rust-colored water, the problem is inside your water heater. Not your well. Not your municipal supply.

Two things cause this. First, sediment builds up at the bottom of water heater tanks over years of use. Minerals and rust particles that settle there get stirred up and come out with the hot water, especially in older tanks or tanks that haven’t been flushed in years. Second, the sacrificial anode rod inside the tank protects it from corrosion by corroding itself instead. Once the anode rod is fully depleted, the steel tank lining starts to rust. The brown water you’re seeing is that rust washing out.

To confirm the tank is the source, run cold water at a nearby faucet. If it’s clear, the problem is the water heater. Full stop.

Fix it in two steps. First, flush the tank. Turn off the heater, attach a garden hose to the drain valve, and drain it fully into a floor drain or outside. If the water runs brown or sandy during the flush and then clears, sediment was the issue. Second, if flushing doesn’t solve it, check when the anode rod was last replaced. Most anode rods last 3 to 5 years. Replacing one costs $20 to $50 in parts and an hour of work. If the rod is visibly corroded down to the wire core, it’s done. Replace it, and the rust problem often stops.

Brown with Particles vs. Brown That Develops After Sitting

The visual appearance of the brown water gives you useful information.

Brown water with visible particles floating in it is particulate sediment or ferric iron. It’s already in solid form. This kind often responds well to a sediment filter at the point of entry.

Brown water that initially looks clear but turns orange or rust-colored after sitting in a glass or white bowl is dissolved ferrous iron oxidizing on contact with air. It won’t be caught by a basic sediment filter. You need an oxidizing filter system that first converts the dissolved iron to a solid form and then removes it. See best iron filters for well water for options.

When Manganese Is the Cause

Manganese occasionally produces brown water, but its color tends toward black-brown or gray-brown rather than the orange-rust color of iron. If the staining in your sinks and tubs looks more black or dark gray than orange, add manganese to your test panel.

Manganese has an EPA health advisory, unlike iron, which only has an aesthetic guideline. It matters more for infants and young children. Read more at manganese in drinking water.

What to Do Right Now

If the brown water appeared suddenly in a home on municipal supply, run your cold tap for 5 to 10 minutes. Call your utility. Don’t drink it until it clears and your utility confirms normal operations.

If only your hot water is brown, flush your water heater this week. If the flush reveals heavy sediment or the water stays brown after flushing, check the anode rod.

If you have well water that’s been running brown for as long as you can remember, get a lab test before buying any equipment. The well water testing guide will walk you through exactly what to order and where to send the sample.

Sources: EPA Iron in Drinking Water | EPA Private Wells