Why Is My Hot Water Brown?

Fill a clear glass from a hot tap and another from a cold tap. If the cold water is clear and only the hot is brown, the water heater is the source. If both are discolored, the problem is upstream, either in the city water supply (often after maintenance or a main break) or in your home's galvanized pipes.

The most serious cause of brown hot water is a tank rusting from the inside. Steel tanks have a glass lining and a sacrificial anode rod to fight corrosion, but over years the lining cracks and the anode gets consumed. Once that protection is gone, the steel begins to rust, and that rust colors your hot water brown or orange.

A rusting tank cannot be repaired. The rust will only get worse, and the tank is on a path to leaking or rupturing. If brown hot water is coming from an older tank, replacement is usually the right answer.

The anode rod is designed to corrode so the tank does not. When it is fully consumed, the tank loses its protection and begins to rust. Replacing the anode rod early, before the tank rusts, can extend the life of a water heater. Once brown water appears, the rod is already gone and the tank may have started corroding, so a technician checks both.

Sometimes brown water is loose sediment that has built up in the tank and gotten stirred into the water after a period of low use or a change in pressure. A professional flush can clear this. If the discoloration returns soon after flushing, the cause is corrosion, not loose sediment.

If both hot and cold water are brown, the water heater is not the culprit. Galvanized steel supply lines can rust internally as they age, and city water disturbances can stir sediment into the supply. A plumber can help isolate whether the issue is your pipes or the municipal supply, and whether repiping is warranted.