Water Corrosion

Corrosion is a chemical process in which the metals commonly used in plumbing systems are eaten away and ultimately fail. Some types of corrosion cause a fairly uniform attack of metals, gradually thinning the entire metal surface often causing "red water" from iron or steel water systems or blue stains from copper or brass systems. Another type of corrosion concentrates its attack in small areas, developing deep in the groun which can also penetrate the wall of a pipe or tank. This type of corrosion usually does not contribute iron or copper to the water, but even a single hole in a length of pipe or a tank can destroy its usefulness.

Corrosion is a perfectly natural process. Man has learned how to convert the naturally occurring ores into useful materials, but all of these metals have a tendency to revert back to their natural stable ore forms. Some metals are highly resistant to corrosion, but these are usually too costly to be used in plumbing systems.

Similarly, all waters are corrosive in at least some degree. However, the rates of corrosion produced by different waters vary widely, depending upon a number of factors. The major factors which govern the rate of corrosion include electrical conductivity due to improper grounding, size of service line, dissimilar metals, improper pipe bedding, corrosive soils, oxygen concentration, and temperature. Each of these factors is discussed in the sections below:

  • Building is improperly ground through the piping system. Construction methods often utilize several procedures to ground the electrical system, one of which is connecting the ground to the water piping. Electrical grounding theories is a vast subject on which differing opinions are written and that while grounding to the water piping system has been common practice for many years and even though a ground rod exists, stray currents will still cause electrolysis and corrosion in pipes.
  • The size of the service line is too small. A high velocity of water running through a small service line servicing a large condo building can cause hydraulic wear on the piping. For example, an existing Wildernest condo has a 2" water line servicing a 20-unit building and in today's standards the County would require a 4" to 6" service line.
  • The amount of galvanic corrosion from the use of dissimilar metals contained in or in contact with the piping system (the use of dissimilar metals such as copper pipe and steel hot water heaters can cause corrosion).
  • The improper bedding of the pipe is a big factor in the deterioration and/or leaks in service lines. Many Wildernest properties were built in the 70's and 80's. The regulation of water pipe construction and installation during that time were minimal. The bedding used at the time included rocks and improper grading, which over time wears on pipes causing failures.
  • Presence of suspended solids, such as sand, sediment, corrosion by-products, and rust can aid in the physical corrosion and damage, damage, and facilitate chemical and biochemical corrosion.
  • Corrosive soils - primary characteristics contribute to the corrosivity of the soil include high chloride content, low electrical resistivity, and low pH.
  • Water Quality - primary characteristics contributing to the corrosivity of the water include high Total dissolved Solids (TDS), low pH, dissolved inorganic carbonate in the water, and high concentrations of chlorides.
  • Other factors include the amount of oxygen in the water and the temperature of the water.

​There are several ways to treat hard water. Some water treatment technologies, such as softeners and aeration systems, can aggravate corrosion. Softeners remove the protective calcium and magnesium and introduce highly conductive sodium into the water. Aeration devices for iron, sulfur, or odor removal add oxygen, which is extremely corrosive in water. Higher water temperatures and suspended materials accelerate the rate of corrosion by increasing the reaction rates or possibly causing physical damage to the pipes.

While the District sympathizes with Wildernest property owners who have experienced service line pipe corrosion, the District cannot take responsibility for the maintenance or replacement of water piping within the consumer's home or business. The District Rules and Regulations clearly state that each property owner must maintain its own internal plumbing system and entire service line.