If you come home after time away in St. Louis and the first water from the tap looks orange, it can be alarming. The cause is often more ordinary than a problem with the whole house. Water that sits still in pipes for days can change color, and iron is one common reason. This guide walks through what to check so you can decide what to do next.

Why water changes after the house sits

Iron is a naturally occurring metal that shows up in many water sources. When water is moving, it usually stays clear. When it sits in a pipe for a long stretch, dissolved iron can oxidize, and fine particles can form and settle. Older steel pipes, galvanized sections, and water heater tanks can also shed small bits of rust that loosen when flow starts again. The result is often a brief orange or brownish tint that clears after the water runs for a while.

That pattern is different from water that is orange every time you turn on the tap. A short-lived tint after time away points toward water that sat in the lines. Constant color points toward the source, the main plumbing, or a specific fixture.

Quick checks you can do yourself

  • Run only the cold tap at the faucet nearest the main entry for a few minutes, then look at the water in a clear glass.
  • Repeat with the hot tap. If only hot water is affected, the water heater or the hot line is the likelier source.
  • Compare several faucets. If one sink is the only orange source, look at that fixture first.
  • Watch whether the water clears as it runs. Clearing water usually means stagnant water, not a continuing supply problem.
  • Fill a white container and let it stand. Particles that settle to the bottom with a rust color suggest iron or sediment.

Hot tap or cold tap?

The answer narrows the search. If both taps are orange, the problem is probably in the incoming supply or the shared main lines. If only the hot tap is orange, check the water heater, the anode rod condition if you know it is there, and the hot branch lines. A heater that has been unused can release built-up rust into the water when flow resumes, so the hot side often clears more slowly than the cold side.

Where your water comes from in St. Louis

Most homes in the city and many suburbs receive water from a municipal supply. Homes in outlying areas may rely on a private well. If you are on a well, iron is more likely to be present in the source itself, and an orange tint that returns after each absence may need a water test rather than a simple flush. If you are on municipal water, the supply is treated and monitored, and persistent color is worth raising with your water provider, but you can still start with the checks above at home.

Flushing the lines

When the color is temporary, running water through the house usually clears it. Start with the cold tap farthest from the entry, since that line has likely been still the longest. Work back toward the entry, running each tap until the water is clear before moving on. Do the hot taps the same way, and do not forget outdoor hose spigots and any laundry or ice maker supply lines.

Clean any faucet screens where you see particles caught in the mesh. Hold off on running the washing machine or dishwasher until the water runs clear, since rust in the water can stain fabric and dishes. If the water heater itself looks heavily stained, or the orange water keeps coming back from the hot side, a licensed plumber can inspect the tank and the hot lines.

When to test or call for help

If the orange water returns after normal use, keeps staining fixtures or laundry, or shows up at only one source, a home water test is a sensible next step. Testing can confirm whether iron is present and help you tell whether the source is the supply, a well, or the plumbing. Collect one sample from the first draw after time away and another after flushing, so you can compare them.

This guide does not say whether any color in water affects health, and until you know what is in your water, do not use orange water for drinking or cooking. If you have questions about health effects, ask a qualified professional or your local health department.