Rusty or brown hot water usually comes from inside the water heater, where the tank or a worn anode rod is corroding, or where sediment has built up. If only the hot water is discolored, the water heater is the most likely source.
Test Hot and Cold Separately
Fill a white cup with cold water, then another with hot water. Compare them. If only the hot water is brown or orange, the problem is likely in the heater. If both are discolored, the cause may be rusty pipes in the house or work on the water main outside.
Common Causes in the Water Heater
- A worn anode rod: this metal rod protects the tank by corroding first. When it is used up, the tank itself starts to rust.
- Tank corrosion: an older steel tank can rust from the inside.
- Sediment: minerals and rust flakes can settle at the bottom and get stirred up.
Other Causes to Rule Out
Old galvanized steel pipes can rust inside, especially in older homes. Rust from these pipes may show up in both hot and cold water. Street work, hydrant flushing, or a main break can also send rusty water into homes for a short time. In those cases, running the cold water for a few minutes often clears it.
When to Worry
Rusty hot water combined with an older tank, moisture at the base, or rumbling noises can mean the heater is near the end of its life. A tank that is rusting through cannot be patched.
Avoid draining the tank yourself if it is old, since corroded drain valves can break and leak.
Having the water heater inspected can show whether a new anode rod or a replacement is the better path. If rusty water appears on both hot and cold sides, you can ask a plumber about older pipes in the house by calling (833) 603-1840.