Everytime there’d be was a splash of rusty water, then clear for the rest of the day??? It turned out the builder had used a black steel nipple to mount the spiggot. 
John Kogel
www.allsafehome.ca
Correction: black steel and thank you very much for all your help 
Most all older Hydronic heat pipes around my area are black pipe like in the picture but I’ve never seen black used for domestic hot supply.
We still have quite a few houses around here that have the old galvanized pipes and are naturally, allowed to remain because they were allowed at the time.
However, most do have poor flow pressure problems and we are replacing them with Pex or copper every chance we get.
We recently replaced our Coal Fired –> Fuel Oil Fired –> Natural Gas Fired Kohler boiler about a year ago. Our home was built in 1900. I did have a chance to visually inspect the inside of the visible distribution pipes and found very little rust and they looked great for the age!
I do occasionally find black-iron pipes in potable distribution systems. Sometimes they are installed on water heaters. Other times they are in other places (see picture). I know they are not preferred. What would be the best way to describe this situation?
I would say black iron
Agree with Jack, that’s black iron. Gas line?
Nope. Part of the potable cold water supply system.
some boilers had chemical feeders on it to prevent rust and build up did your happen to have that?
No it didn’t. In fact, it didn’t even have a back-flow preventer. It was a very basic hot water boiler system.
The condensing boiler that replaced it is fantastic. It’s only 23" x 16" x 16" h x w x d.
That was my take on it ( both issues) as well, but I waited until I had read all the posts before I commented.
P.S. - in reference to piping failures, I have seen pinhole leaks develop in copper tubing in less than 10 years of service when the piping was not bonded to the system ground.
Looks like gas pipe used incorrectly for water supply.
:mad: