Why Is My Hot Water Rusty?
If only the hot water is rusty, the water heater is the likely source: a worn-out anode rod has let the steel tank start corroding inside. If hot and cold are both discolored, look at your pipes or your water provider instead. Run each tap separately, compare the colors, and you'll know where to start.
Rusty water isn't usually a health emergency, but it stains fixtures and laundry, and when it comes from the heater it's an early warning about the tank. Older galvanized steel pipes, where a home still has them, can cause it too, so the test below is worth doing before anyone touches the heater.
The Hot-Only vs. Hot-and-Cold Test
- Pick a tap close to the heater. A bathtub or laundry sink works well because the flow is strong.
- Run the cold water only. Fill a white cup or a clear glass after about 30 seconds of flow. Note the color.
- Run the hot water only. Let it run until it's fully hot, then fill a second cup. Compare them side by side.
- Repeat at a tap far from the heater. This tells you whether it's one spot or the whole house.
| What you see | Most likely source |
|---|---|
| Hot is rusty, cold is clear | The water heater: anode, tank lining or a steel fitting at the tank |
| Both rusty at every tap | The water main or the supply line into the house |
| Both rusty, worse at certain taps or first thing in the morning | Galvanized pipes inside the house |
| Rusty at first, then clears in a minute | Rust that sat in a pipe overnight; often galvanized pipe |
When the Water Heater Is the Source
How does a tank start making rusty water?
A tank heater is a steel shell with a thin glass lining inside. The lining always has tiny gaps. To protect the steel at those spots, the tank has an anode rod, a metal rod that corrodes on purpose instead of the tank. In water as hard as Apache Junction's, about 13–16 grains per gallon, that rod can wear down faster than people expect. Once it's mostly gone, the bare spots in the lining start to rust, and that rust shows up in your hot water.
If the tank is still fairly young and dry, a new rod may slow things down. Our anode rod replacement page covers rod types, how we check them, and when a new one is worth it. If your hot water also smells like rotten eggs, that's a separate anode reaction, also covered on that page.
Could it be a fitting and not the tank?
Sometimes. Steel nipples where the pipes connect on top of the tank can rust inside, especially on older installs with no dielectric unions. That rust tints the water but doesn't mean the tank itself is failing. We look at the top fittings before calling a tank done.
What about rust I can see on the outside?
Rust on the outside of the tank, at the base or around the fittings, often means water has been seeping for a while. That's a different and more serious sign than discolored water. Our guide on a leaking water heater tank explains how to tell a fitting drip from a tank that's rusting through.
When It's the Pipes or the Water Provider
Do galvanized pipes cause rusty water?
Yes, and they're common in older homes and some mobile-home parks. Galvanized steel pipe has a zinc coating that wears away over decades. The steel underneath then rusts from the inside. You often see rust first thing in the morning or after the water sat unused, and it may be worse on the hot side because warm water speeds up corrosion. The only lasting fix is repiping the affected lines, which is a plumbing job beyond the heater.
Could work on the water main cause it?
Yes. When crews from your water utility, which here is either the Apache Junction Water District or Arizona Water Company depending on the street, repair a main, flushes hydrants or changes pressure, sediment and rust in the mains can get stirred up. Both hot and cold turn brown, usually for a few hours. Run a cold tap outside or in the tub until it clears. Avoid running hot water or doing laundry until then, so the dirty water doesn't get pulled into your heater. If it lasts more than a day, call your water provider.
What if hot water from the heater got dirty during main work?
If you ran hot water while the mains were stirred up, some of that sediment may now be in your tank. Once the cold water is clear, a short drain from the heater's drain valve into a bucket usually clears it.
What to Check Before You Call
- The age of the tank. The date is coded in the serial number on the rating label. Our guide on reading a water heater's age shows how.
- A bucket test from the drain valve. Drain a gallon or two from the heater into a white bucket. Rusty water and orange grit point to the tank.
- The base and fittings. Look for rust streaks, crusty fittings or damp spots under the tank.
- The temperature setting. About 120°F suits most homes. Higher settings speed up corrosion and scale.
Will flushing the tank get rid of rusty water?
It can, for a while. A flush clears loose rust and sediment from the bottom of the tank, and if the anode still has life in it, the water may stay clear. If the lining is failing, rust comes back within weeks, because the source is the tank wall itself. Our flushing guide walks through the steps if you want to try it first.
When Rusty Water Means the Tank Is Done
Rusty hot water on an older tank is one of the clearest signs that it's near the end. Once the inside is corroding, the rust keeps eating at the steel until a pinhole opens, usually at the bottom or a seam. That might be months away or much sooner, and nobody can predict the day.
- The tank is about 8 years or older, and the hot water stays rusty after a flush
- The anode rod comes out as bare wire
- You see moisture under the tank or rust at the bottom seam
Any two of these together usually mean it's time to plan a replacement before it fails. In a garage near finished floors, or a mobile home water heater closet over a particleboard floor, a leak does more damage than in most places. Our repair or replace guide helps with the decision, and our water heater replacement service explains how a swap works. If water is already on the floor, our Apache Junction leak repair team is open 24/7 at +1 480-863-0807.
Brown Water From a New Water Heater
A brand-new tank shouldn't make rusty water, so when it shows up right after an install, look elsewhere first. Shutting off the main and draining the lines can knock loose rust and scale in older pipes, and that clears with a few minutes of running the taps. Reused steel nipples or old connectors at the tank can also tint the water.
If the hot water is still brown after a few days of normal use, while the cold is clear, call the installer and have them look before the manufacturer's warranty becomes a question. For warranty basics on young tanks, read about a new water heater that's leaking.
Rusty Hot Water FAQs
Is it safe to shower in rusty hot water?
For most people, short-term contact with rust-tinted water isn't considered a health risk, though it can stain skin, hair, tubs and laundry. The bigger concern is what it says about your heater or pipes. If the water also smells unusual, looks cloudy for days, or your provider has issued a notice, follow their guidance and ask them about testing.
Why is my hot water rusty only in the morning?
Water that sits overnight in rusting pipes or a corroding tank picks up more iron, so the first draw is the worst. If it clears after a minute and only the hot side does it, the tank or a steel fitting near it is the likely source. If both sides do it, galvanized pipes in the house are more likely.
Can rusty hot water ruin my laundry?
Yes. Iron in the water leaves orange or yellow stains that are hard to wash out, and bleach can set them. Run the cold tap until it's clear and wash on cold until you find the source. If clothes already have rust stains, a rust remover made for fabric works better than another wash.
Can I cook with hot tap water that looks rusty?
It's better not to. A common rule is to use cold tap water for drinking and cooking anyway, because water that sits in a tank or warm pipes can pick up more metal and sediment. Rust in the hot water is one more reason to stick with cold. Heat cold water on the stove instead, and find the source of the rust.
Will rusty hot water clear up on its own?
If it came from main work or a pipe disturbance, yes, usually within hours to a day. If it comes from the water heater, no. A corroding tank keeps making rust, and the color often gets worse over time. Rust that hasn't cleared within a couple of days of running the taps needs a closer look at the heater or the pipes.