Rust stains in sinks and tubs come from iron, which leaves orange or reddish-brown marks where water sits and dries. Phoenix city water tested from not detected to 30 ppb iron, far under the EPA's 300 ppb stain threshold, so the iron usually comes from inside the house: galvanized pipe, a rusting water heater, or a well.
Is the iron coming from city water or from your house?
On City of Phoenix water, most likely your house. Phoenix's 2025 water quality report lists iron in its delivered water ranging from not detected to 30 parts per billion, against the EPA's 300 ppb secondary level. That's at most one tenth of the level where the EPA flags staining.
City water can still carry rust briefly, for example after work on a nearby main. That kind of event clears, and our page on why tap water turns brown covers what to do. Steady stains that build week after week point somewhere else.
Here's how to narrow it down:
| What you notice | Likely source |
|---|---|
| Stains only where hot water runs, or rusty hot water | Water heater tank corrosion |
| Stains at every fixture, plus low pressure, in an older home | Galvanized steel supply pipe |
| Stains on a private well, water clear at first | Dissolved iron in the groundwater |
| Stains only under one dripping spout | A drip plus a little iron, or a rusting fixture part |
| Pinkish or orange slimy film, not a hard stain | Often a bacterial film, not rust |
Why does the water look clear if it's leaving rust?
Because dissolved iron is invisible until air gets to it. Penn State Extension explains that water with high iron "may appear colorless initially but orange-brown (iron) or black (manganese) stains or particles quickly appear as the water is exposed to oxygen." It calls this the "reduced" form of iron, dissolved in the water.
That's the classic pattern on a private well. On city water, clear water that still stains is more likely picking up small amounts of iron from corroding pipe or a tank in your home, which then shows up where water sits longest. Toilet bowls and tub drains get the worst of it because water stands there.
Which parts of a Phoenix home add iron to the water?
Galvanized pipe, the water heater and private wells are the usual sources of iron in a Phoenix home:
- Galvanized steel pipe. Older homes may still have it. The City of Phoenix explains that galvanized pipe is "coated with zinc to prevent corrosion and rust," and that the zinc coating corrodes over time. The city stopped using galvanized service lines in 1983. As that coating wears, the steel underneath can rust, and the EPA notes that corrosion of iron and copper "may stain household fixtures." Our page on signs of old, failing pipes covers what else to look for.
- The water heater. A steel tank can start to rust once its protective anode rod is used up. Stains that line up with hot-water use are the clue. See why only the hot water is brown.
- A private well. Well water can carry dissolved iron. Penn State recommends testing when you see orange-brown stains or taste metal, and our page on common Arizona well water contaminants covers what to test for.
Are rust stains a health problem?
No, rust stains are not a health problem in themselves. Penn State Extension says "Iron and manganese are not health concerns in drinking water," and that they carry secondary standards because of staining and a bitter metallic taste. The EPA likewise classes iron as a nuisance chemical.
The thing to watch is what the stains say about your pipes. Galvanized pipe that is rusting can also be a lead concern, because the City of Phoenix says the corroding zinc coating can potentially leach lead particles in galvanized service lines. If you have galvanized pipe, read how to tell if you have lead pipes and consider a lab test.
How do you get rid of rust stains for good?
Clean the stain, then remove the iron source, or it comes back.
Cleaning. Use a rust remover labeled for your fixture's material, whether porcelain, enameled cast iron, acrylic or stainless, and follow the label. Test a small hidden spot first. Our page on rust spots on a stainless sink covers that finish.
Fixing the source:
- 1Water heater: flush it and check the anode rod. A tank that's rusting through needs replacing.
- 2Galvanized pipe: spot repairs only buy time. A repipe in PEX or copper replaces the rusting steel. If the galvanized pipe is the city's service line, Phoenix says it will contact you about replacement.
- 3Well water: test first. Penn State notes a softener can remove some dissolved iron under certain conditions, while higher or oxidized iron needs filtration, so the test result decides the equipment.
- 4Dripping fixture: fix the drip so water stops pooling.
HQ Plumbing & Air handles water heater service, galvanized pipe repair and repiping across the Valley through our residential plumbing service. We're licensed and insured, and we give free estimates with upfront pricing.