Note to readers: This post was updated on July 24, 2026 to reflect current guidance on sediment and pipe corrosion causes and add links to our related water quality guides. We refreshed the details below so the advice reflects how we approach this work today.
One day your water is clear, and the next it’s running brown or rust-colored out of the tap. It’s alarming to see, but in most cases brown water is a sign of sediment or mineral buildup rather than a health hazard. Here’s what usually causes it and when it’s worth calling a plumber.
Water Heater Sediment
The most common cause of brown water, especially from hot water taps, is sediment buildup inside your water heater tank. Minerals settle at the bottom of the tank over years of use, and when disturbed — by heavy usage, a temperature change, or the water heater simply aging — they get pushed into your hot water lines. If your water heater is more than 8-10 years old, this is often the culprit.
Corroding Pipes
Older galvanized steel pipes rust from the inside out over decades. As the interior corrodes, rust particles flake off into the water supply, which is more likely to show up right after water has sat still in the pipes for a while (like first thing in the morning). This tends to affect the whole house rather than a single fixture.
Municipal Water Main Work
If the brown water shows up suddenly and affects your whole neighborhood, it’s often related to water main repairs, flushing, or a break somewhere in the city’s distribution system that stirred up sediment. This usually clears up within a day or two on its own.
Is It Safe?
In most cases, brown water from sediment or mineral buildup is not a health hazard, though it’s understandably unappealing to drink or use. That said, if the discoloration persists for more than a couple of days, only affects hot water, or comes with a strange smell, it’s worth having it checked rather than assuming it will resolve on its own.
What to Do About It
Run cold water taps for a few minutes to see if it clears — if it does, it was likely a temporary sediment disturbance. If only hot water is affected, your water heater tank may need to be flushed or, if it’s older, replaced. Homes with persistent mineral or sediment issues throughout the plumbing often benefit from a whole-house water filtration system, which reduces the sediment load hitting your pipes and fixtures in the first place.
Still seeing brown water after a few days? Have your water heater inspected or give us a call and we’ll track down the source.
