Water is the most abundant nutrient in our body and plays an important transmission function in every body cell and tissue. Sixty percent of our body weight is water. The fact that you can live without food for a long period of time, even months, but live only for a few days without water is true.
The addition of zinc, a sacrificial anode, would prevent the iron metal from corroding. According to the table of Standard Reduction Potentials, the standard reduction potential of zinc is about -0.76 volts. The standard reduction potential of iron is about -0.44 volts.
Re: Black iron pipe. Sure are. Black iron pipe is cast from several grades of ductile or malleable iron whereas carbon steel pipe is generally wrought welded or seamless. Cast iron pipe is used for underground or submerged applications and for main steam pipes and branches that are subjected to acids.