In a newly remodeled bathroom, there is an overhead "rainhead" shower and a diverter to a handheld. Typically I turn on the water with the handheld, wait until it's hot, then turn the diverter to the overhead. At that point, the first water out of the overhead is rusty. It clears in a few moments. Where do you think the problem is originating? The water out of the handheld is never rusty. The rainhead is mounted on a chrome pipe coming out of the ceiling of the shower. Is it possible that the chrome is just a sleeve covering a galvanized pipe that could be causing this problem? Although the plumbing for the bathroom was copper, I think I remember seeing a different kind of pipe (galvanized?) coming out of the ceiling while the shower was under construction. What would be involved in fixing this problem? Many thanks for your help.

"I remember seeing a different kind of pipe (galvanized?) coming out of the ceiling while the shower was under construction."

Galvanized pipe can build up rust in the pipe walls and stain the water. The solution would be to replace the galvanized pipe. Regards, Tom

Since this is new construction, including the overhead pipe, why is this happening (even if the new pipe is made of galvanized material)? I was under the impression that this is a problem that develops with old pipes. Can a new pipe have this rust problem? Did my contractor use the wrong material?

"Since this is new construction, including the overhead pipe, why is this happening?"

The water heater isn't new is it? This is where rust can build up if it isn't flushed on a regular basis. If it's not coming from any galvanized pipe.( why did the plumber use galvanizes pipe? ) in the system then the water heater's the most likely culprit. If you don't flush your heater, let me show you how.
For long life and fewer troubles you should keep your heater clear of mineral build-up by flushing on a regular schedule. Attach a hose to the boiler drain at the bottom of the tank. With the pressure on, open the boiler drain and let it run until the water runs clear. You will see a spurt of red,(rust) followed by white grains,(lime or calcium carbonate). This shouldn't take more then a few minutes. Do this monthly to keep it clear. Now flush out your hot water lines on ALL fixtures. Now pull each aerator and clean the screens. Be sure you put them back togather the same way you took them out. Don't forget to flush it out every month. Your heater will thank you for it. Hope this helps, Tom

Thanks Tom, but I don't think it's a water heater problem because we have a Takagi tankless system. So... any other thoughts? I'm only guessing about the galvanized pipe overhead. What would ordinarily be used, if not galvanized? Again, this is the piece of pipe sticking down from the ceiling of the shower, which I think has a chrome sleeve over it, and the shower head is attached to it. Could this be the only source of this problem (since the handheld never has rusty water, even when turned on first)? Thanks again.

If the shower raiser's galvanized then that could very well be the cause of the rusty water. This would affect the shower head and not the hand held.
Regards, Tom