# Why is brown or rusty water coming out of the tap?

> Rusty water from a faucet: tell galvanized pipe from the water heater, City main work and sediment, read hot-only or first-draw color, then decide who to call.

URL: https://chicagolakerepiping.com/guide/rusty-brown-water-from-tap/

Learn

The color alone does not name the source. Which taps, hot or cold, first draw or all day, and what happened on the street this week narrow it down before anyone blames the pipes.

Last Updated: October 25, 2026

**Rusty or brown water from a faucet comes from one of four places: corroding galvanized pipe inside the house, the water heater, work on the City’s water mains, or sediment stirred loose in the lines.** If only the hot side is brown, suspect the heater. If every tap runs brown and then clears, suspect the street. If certain fixtures run brown at the first draw, suspect the pipe feeding them.

The color tells you iron is in the water. It does not tell you where it came from, and the fix for each source is different. [Chicago Lake Repiping](https://chicagolakerepiping.com/) offers and manages [galvanized pipe replacement](https://chicagolakerepiping.com/galvanized-pipe-replacement/) and [whole-house repiping](https://chicagolakerepiping.com/whole-house-repiping/) across Chicago and nearby Cook County suburbs, with licensed and insured plumbing contractors doing the work, and the pattern-matching below is how a walk-through decides whether the pipes are the problem at all.

Key takeaways

- Hot side only: the water heater or the hot lines leaving it.
- Every tap at once, clearing after a while: City main work, hydrant flushing or a disturbance upstream.
- Certain fixtures at the first draw, returning after the water sits: the galvanized pipe feeding them.
- After plumbing work: scale loosened inside old pipe, which can settle in aerators and valves.
- Rust color does not show whether lead is present. A free City water test does.

## Read the pattern

| What you see | Likely source | Next step |
| --- | --- | --- |
| Brown water from hot taps only | Water heater sediment or rust; hot-side galvanized | Have the heater checked and drained; compare with the cold side |
| Every tap, hot and cold, at the same time | City main work, hydrant flushing, a disturbance upstream | Flush per the City’s instructions; report through 311 if it does not clear |
| Some fixtures, at the first draw, clearing after a minute | Galvanized branches to those fixtures | A plumber’s look at the pipe feeding them |
| Constant tint at every fixture in a house with old steel pipe | Galvanized throughout, possibly the service line too | Check the pipe at the meter and the pipe leaving it |
| A burst of brown after plumbing work or a shutoff | Scale loosened inside old pipe | Clean aerators and screens; flush |
| One faucet only | That faucet’s supply, valve or aerator | Clean the aerator; check the stop valve |

The table’s “likely source” is a starting point, not a diagnosis. Two sources can run at once: an old heater in a house with galvanized hot lines can produce the same hot-side color from both.

## Galvanized pipe corroding inside

Galvanized steel is pipe coated with zinc. The zinc wears through from the inside over decades, and the bare steel rusts. Rust and scale build up on the inner wall and break loose in flakes, especially when water that has sat still starts moving again. That is why galvanized gives itself away at the first draw: the water that sat overnight in a rusty branch comes out tinted, then clears as fresher water arrives from the main.

Hot lines can corrode faster than cold, because warm water speeds the reaction. The same pipe that tints the water also narrows, so rusty water at certain fixtures and weak flow at the same fixtures point the same way. The [low water pressure guide](https://chicagolakerepiping.com/guide/low-water-pressure-old-chicago-house/) covers that side of it, and the [cornerstone guide to galvanized pipes in Chicago homes](https://chicagolakerepiping.com/guide/galvanized-pipes-chicago-homes/) explains the whole failure.

You can check what the pipe is in the basement: galvanized is gray, threaded and holds a magnet. The [guide to identifying your water pipes](https://chicagolakerepiping.com/guide/how-to-identify-your-water-pipes/) shows how.

## The water heater

A tank water heater collects sediment at the bottom and can rust inside as it ages. When that is the source, the color shows up on the hot side and the cold side runs clear. A plumber can drain the tank and look at what comes out, and check the connections and the pipe leaving the heater. If the hot lines are galvanized, they can be part of the problem too, which is why comparing a hot tap and a cold tap at the same fixture is the first test.

Replacing a heater does not fix galvanized hot lines, and repiping does not fix a rusting tank. Knowing which one it is avoids paying for the wrong job.

## City main work and sediment

When every tap in the house runs brown at once, hot and cold, the cause sits upstream of the meter: work on a water main, hydrant flushing, or a change in flow on the block that stirs up sediment in the lines. That water reaches every fixture equally and tends to clear as the lines settle.

Lead-Safe Chicago, the City’s lead program, says that after work on the water mains outside your home, or after a house has sat vacant, you may need to flush more extensively than the everyday routine, and it publishes flushing instructions. When main work is scheduled on a block, the City offers eligible homes a free water filter set certified to remove lead. If brown water at every tap does not clear after flushing, report it through 311, the City’s line for water service problems.

## After plumbing work or a shutoff

Cutting into old galvanized, or shutting the water off and turning it back on, shakes loose rust and scale that were stuck to the inside wall. The result can be a burst of brown water and clogged aerators, a toilet fill valve that sticks, or a faucet that suddenly runs weak. On a repipe, that is why the system is flushed after each cutover and the aerators and screens are cleaned before the job is done.

The City recommends cleaning faucet aerators at least once a month in any case, because sediment, rust and metals collect in them.

## Rust color and lead are different questions

Rust is iron. A brown glass of water says nothing about whether lead is present, and clear water does not prove it is absent. In Chicago the first lead concern is the service line: Lead-Safe Chicago says service lines were primarily made of lead until the federal ban in 1986, and lead can also come from old faucets, solder and interior lead pipe. Galvanized pipe downstream of a lead line can hold lead particles in its rust, which is why the City’s inventory has a [galvanized requiring replacement](https://chicagolakerepiping.com/guide/galvanized-requiring-replacement/) category.

The City’s guidance is to run the water for at least five minutes after it has sat six hours or more, and to drink and cook only with cold water, since hot water can dissolve lead more quickly. Any Chicago resident can request a free lead test kit through 311 or the City’s water quality site. That test, not the color, tells you what reaches the tap.

## When to call the City and when to call a plumber

**Call 311** when every tap runs brown at once, when the color follows work on the street, when you suspect a leak on the service line, or to request a free lead test.

**Call a plumber** when the color shows up only on the hot side, only at certain fixtures, only at the first draw, or after plumbing work inside the house. Those patterns point at the heater or the interior pipe, which are the owner’s to fix.

If the source is galvanized pipe inside, the choice is between a [partial repipe](https://chicagolakerepiping.com/partial-repiping/) of the branches that tint the water and a whole-house repipe that leaves no old supply pipe in service; the [two-flat repiping](https://chicagolakerepiping.com/two-flat-repiping/) page covers buildings with two units, and [lead service line replacement](https://chicagolakerepiping.com/lead-service-line-replacement/) covers the line from the street. Call the number on this page or use the estimate form to set up a walk-through that starts at the meter.

## Questions about this guide

### Why is my hot water rusty but the cold water is clear?

When only the hot taps run brown, the water heater and the pipe leaving it are the first suspects. An old tank can shed rust and sediment, and galvanized hot lines can corrode faster than cold ones because warm water speeds the reaction. Have the heater checked before deciding the whole system needs replacing.

### Why is my water brown after the City worked on the street?

Water main work and hydrant flushing can stir up sediment in the lines, and that water reaches every tap in the house. The City's guidance is that after main work outside your home you may need to flush more extensively. If brown water at every tap does not clear after flushing, report it through 311.

### Should I call 311 or a plumber about brown water?

Call 311 when every tap runs brown at once, when it follows work on the street, or when you suspect a leak on the service line. Call a plumber when the color shows up only at some fixtures, only on the hot side, only at the first draw, or after plumbing work inside the house.

## Related service

### Galvanized pipe replacement

Galvanized pipe replacement swaps restricted steel supply pipe for copper, with code-listed transitions wherever old pipe stays and a flush after every cutover to clear loosened scale.

## More guides

- Learn [Galvanized pipes in Chicago homes: what to do about them](https://chicagolakerepiping.com/guide/galvanized-pipes-chicago-homes/)How to tell whether a Chicago bungalow, two-flat or greystone home still has galvanized steel supply pipe, what its symptoms do and do not prove, and how Chicago's code, permits and lead rules shape the fix.
- Learn [Why is the water pressure low in my old Chicago house?](https://chicagolakerepiping.com/guide/low-water-pressure-old-chicago-house/)Weak water flow upstairs has more than one possible cause, and a repipe only fixes one of them. Here is the order to rule them out, from the street to the shower head.
- Learn [How can you tell if your pipes are galvanized, lead or copper?](https://chicagolakerepiping.com/guide/how-to-identify-your-water-pipes/)A magnet, a coin or key and five minutes at the basement wall tell most pipes apart. Here is what galvanized, lead and copper pipe look like, how to test each without damaging anything, and what stays hidden until a wall is open.
- Learn [What does 'galvanized requiring replacement' mean in Chicago?](https://chicagolakerepiping.com/guide/galvanized-requiring-replacement/)The label on Chicago's service line inventory describes the pipe from the street, not the pipes in your walls. Here is where it comes from, why galvanized is treated like lead, and what to do with it.
- Decision Guide [Should you repipe after your lead service line is replaced?](https://chicagolakerepiping.com/guide/repipe-after-lead-service-line-replacement/)A lead service line replacement brings a new copper service to the basement wall. Whether the pipe it now feeds should go too depends on what that pipe is, where the new line comes in, and how the two permits fit together.