“I never drink water. That is the stuff that rusts pipes.” ~WC Fields
A noted comedian, we can only hope that WC Fields was exaggerating. Aside from the personal health concerns raised by Mr. Fields’ declaration, he does raise an interesting point about the necessity for corrosion control in our water treatment and distribution systems. Rust is just one of many forms of corrosion that can affect our water supply. There is electrical corrosion, chemical corrosion, physical corrosion and biological corrosion. Water alone is insufficient to rust, or corrode, pipes.
Electrical corrosion is simply the transfer of electrons from an anode to a cathode; the process breaks down the place where the anode is situated and begins to build up where the cathode is located. If a pipe is near electrical lines, there may be stray electrical current that will cause this sort of corrosion.
Chemical corrosion has to do with the chemical makeup of the water flowing through the pipes and the reaction of the pipe material. Factors in chemical corrosion include alkalinity and pH levels, dissolved oxygen, hardness, and trace metals.
Physical corrosion deals more with the makeup of the distribution system and the amount of water being distributed. Flow rate can increase corrosion. Having pipe connections that are of incompatible metals will result in corrosion (which also falls under electrical corrosion, as there is a transfer of energy between differing metals). Outside factors include temperature, or soil makeup.
Biological corrosion directly relates to the bacteria present in water while traveling through pipes. There are iron bacteria, and sulfate-reducing bacteria; both thrive in the environment a water pipe provides.
For more detail on corrosion control, you can check out our one-hour online course.