Black iron & water heater

Can black iron be used at the hot & cold water at the top of the tank?

If no why so?

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I found thin — Uniform Plumbing Code 2003

604.1 Water distribution pipe, building supply water pipe, and fittings shall be of brass, copper, case iron, CPVC, galvanized malleable iron, galvanized wrought iron, galvanized steel, PEX or other approved materials.

Yes. It most certainly can. . .


I have never seen black iron at the top of the tank. Just wanted to make sure.

It’s very common to see black iron pipe used for fire sprinkler piping in commercial applications.
It was once common for residential water piping but lost favor due the potential of rusting out.

You will get spanked here for using black iron on water not allowed.

It can be used but it is not recommended because the rust partials break off and spread to the rest of the system. It will also destroy the glass liner of the water heater. i always recommend that it be replaced.

The use of black iron on sprinkler sys and boilers is ok because that water is not oxygenated

Does it give the water a bad smell / taste?
If not, what does?

I’m not sure I’m following you there, Henry.

Various chemicals in the water.

My brother’s house in eastern Slidell, Louisiana, has water that smells like rotten eggs all the time. And the ice cubes are always yellow. Hmmmmmm. The whole neighborhood has rotten egg-smelling water. They were hoping that when Katrina washed away all the houses it would have washed away the bad water, too, but no such luck. New house, old smell.

Sprinklers and boilers are closed systems as long as you do not add more fresh water the oxygen in the water separates. When the oxygen is gone there is no more rusting. on a domestic system you are always running water so you are putting fresh oxygenated water back in the system.

Those two systems are only “closed systems” for a period of time. As soon as they are used, which you acknowledged when you said “as long as you do not add more” water, then it is an open system for that period of time. No system outside of the laboratory can be completely closed, only closure to varying degrees.

Water (H2O) is not water without oxygen. . .

True but when water is not moving it gets stagnant and the air separates. so the air is not in contact with the pipe like it is in a domestic system. Its just like the difference in a dead lake and a stream. a dead lake has no movement so it gets stagnant it looses its oxygen and a running stream is always moving so it gets aireiated.

If it’s a closed system, and “the air separates,” where does the air go?

An (automatic) air bleed valve removes the air from the system.

On a boiler it goes to an auto air bleeder or a separator tank. on a fire sys it just goes to the highest point. Thats where you will find rust or sludge.

So then we’re back to the point where there is air in the system which can cause rust.

No we are not. :roll:

Yes but it is a miner amount. not like a domestic sys.