Is the loss of the zinc layer in galvanized piping.
When general, uniform corrosion rate is high, piping
often fails by rapid loss of zinc layer. After 75% of
zinc loss, piping corrodes as if there were no coating
applied.
Release of metals
A by-product of general, uniform corrosion is release
of metals into solution. Most commonly found are
zinc and iron, with the possibility of lead and cadmium.
Lead and cadmium are common impurities of zinc.
Pitting
A chemical reaction between zinc and iron in flowing
water. Pitting may shorten pipe life by 10 times.
Tuberculation
The development of round bulges inside of piping.
These protrusions obstruct flow of water.
Note: The rate of corrosion will vary due to water
quality and manufacturing processes of galvanized
pipe.
Other materials
Synthetic piping (Petroleum based plastics)
React adversely to chlorine and other chemicals
used in water treatment. The chemical reaction
causes the interior of piping to dry, crack and flake.
Eventually, system failure.
Note: The history of synthetic water supply piping
is not as consistent as copper piping.
