Q: What causes rusty water, and is it safe to drink?
A: Rust is oxidized iron. It can originate anywhere from a water main to your own plumbing. Tap water can turn reddish brown due to iron particles that break free from sediment inside corroded iron or steel pipes. Corroded pipes are common in North American cities, where some water systems are more than 100 years old.
Iron also occurs naturally in some drinking water sources. If the water is exposed to air before coming out of the tap, it, too, may be rusty or turn rusty after standing.
Though rusty water may look and taste unpleasant—and possibly stain sinks and clothing—it is not a health concern. A possible exception is people with hemochromatosis, a rare disorder that causes excess iron accumulation in body organs.
On its own, rust in water is not a sign of harmful bacteria or lead, which are hazards. In fact, the limits set by the Environmental Protection Agency (EPA) for iron in drinking water are based on aesthetics (taste, odor, color), not safety concerns.
You’ll know the problem is in the pipes in your house or apartment building, not the municipal water supply, if rust appears only in hot water, comes only from certain faucets, or clears after running for a short time. You can filter the water if it bothers you, but you may want to consult an experienced plumber or water-quality expert to find out what device will work best (treatment depends on the form and amount of iron in your water).
A sudden appearance of rusty water, however, can occur if a water main breaks, a fire hydrant is activated, or some other disturbance causes an increase or change in water flow. In such cases, you may be notified and told not to use the water until it clears; if the problem persists, call your local water department or Department of Health.