Fixing Rusty Hot Water and What Causes Discolored Water

Troubleshooting rusty hot water in the electric and gas water heaters. What is the cause of the discolored water, and why do I see rusty or brown water coming out of the tap and in the tub?

Is it dangerous?

Reasons for rusty or discolored hot water appearance

With the first signs of the discolored hot water, often found as rusty or brown, many consumers will assume that their gas or electric heater got corroded. So, is the rusty fluid result of the rusty tank, or is something else going on?

There are several reasons for the rusty appearance:

Why do water heater tanks corrode?

Rusty waterphoto: pixabay

If you look at most tank-type heaters today, no matter electric or gas-powered ones, you will see that almost all of them are equipped with a metal tank. The inner surface of the metal tank is exposed to different water conditions, and corrosion is one of the problems that can occur.

To prevent corrosion and rusty tank, the manufacturers would cover the tank with the glass-porcelain coating, treated with the high temperatures. Such technology prevents the tank from rusting. The anode rod is another element that is used to protect the metal components from corrosion.

If, for any reason, the glass lining is cracked, hot water can get in touch with the metal, start the chemical reaction and after some time corrode the tank. Every time the hot water draws, water will contact the rusty spots developed on the tank, get contaminated, and change the color to brown.

Rust particles and dirt from the water supply can also accumulate on the bottom of the water heater. When you turn the heater on, a sudden move stirs up the water, making the hot water brownish at the tap.

Bacteria as the result of the rusty hot water

The iron-reducing bacteria, which is usually found in the soil, wells, and water distribution systems, is the bacteria that can make water have a rusty look. Soluble iron is food for bacteria, which will, with the lack of oxygen and no water movement inside the tank, reduce the anode rod efficiency and speed up the corrosion.

Water mains

The main pipeline made of cast iron pipe or metal could also rust, delivering stained water to your home when used. To confirm the problem with the municipality water, first, check around to see if your neighbors are having the same problem. If other homes are affected, the only thing you can do is flush your plumbing system for at least half an hour. You can repeat it several times until the water runs clear.

There could also be repairs on the main supply line and even bursts down the road. As rust accumulates in water mains, and when hydrants in the area are flushed (or used by firefighters), this will disturb the normal water flow and pick up the rust particles, which will end up in your sink or shower.

Deposits in water

Incoming water might bring clay, mud, and sand deposits if your home plumbing is connected to the well system. If there is a break in the central plumbing system or new houses are built in the area, the dirt, mud, and clay will enter the pipeline system and mix with water, resulting in a brown or rusty appearance.

Also, any disturbance of sediments inside the water tank can cause brown particles to appear in the water.

Now, as your heater is between the tap and central plumbing, it will collect the dirt coming from the outside supply pipeline so that the hot water will have this rusty or brown color look.

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Rusty pipes

If the brown water is coming from the cold water tap, rusty pipes should be blamed. Rust usually forms sediments that settle on the bottom of the pipes. Once the pressure inside the pipe changes (increases) or something else stirs up, eventually, they will appear at the tap. The best solution is to replace a deteriorating pipe.

If your plumbing is using galvanized pipes, they could rust over time. However, if the plumbing consists of copper or plastic tubes, then you should look for the cause somewhere else.

Pipes can also rupture, so dirt can slowly get inside, contaminate the water, and making it look rusty.

Universal solution for the rusty hot water

One solution for the rusty hot water, excluding hard conditions such as a rusty tank, is to drain and flush the tank thoroughly through the drain valve. If the heater tank and plumbing system are infected with the bacteria, shock therapy with the chlorine, followed by flushing, should be applied.

Most of the time, heaters are blamed for the rusty hot water and other changes in color. Keep in mind that both electric and gas-powered heaters are built with quality tank glass lining, so it is rare to see cracks in the lining that will allow water to contact the metal tank and get corroded.

If your water heater is over 10 years old and hot water comes out brown often, it is time to replace it.


Most of the time, rusty hot water is not harmful if you want to shower or brush your teeth, but it is not recommended to drink, and it can discolor dishes and clothes. It is not appealing to see, and it can smell and taste bad.

To prevent further and more severe problems, it should be taken care of on time. Water heater manufacturers recommend regular maintenance, such as flushing, to clean out the sediments and rust, ensure better performance, and at the same time extend the life of the unit.

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