![]() Influence of ionic impurities on corrosionĬhemical additives are added to water during the water treatment process. Therefore, the interior or exterior surfaces of the pipe can provide locations for an electrochemical cell which can start the process of pipe corrosion. The galvanic interaction of different metals has a significant role in pipe corrosion, because many commercial metals are alloys of various metals. An example that many people are familiar with is zinc galvanizing of steel, where the zinc surface coating protects the steel from rusting. Metals lower in the galvanic series more negatively charged will sacrifice their electrons to metals higher in the series. The galvanic series of metals is the hierarchy of which metals will release their electrons to other metals. Galvanic properties between dissimilar metalsĪll metals have slightly different properties, and galvanic differences are the tendency of one metal to release electrons to another metal. The corrosive electrical potential is typically created by differences in the types of chemicals in soil or the surface of the metal pipe. An electrochemical cell can be thought of as a battery, with an electric current between a positive potential (anode) and a negative potential (cathode). When metal pipe corrosion occurs, it is a result of the electrochemical electron exchange resulting from the differential galvanic properties between metals, the ionic influences of solutions, aquatic buffering, or the solution pH.įor corrosion of metal water pipes to occur, an electrochemical cell must be present. Under certain environmental conditions, metal pipes can become corroded based on the properties of the pipe, the soil surrounding the pipe, the water properties, and stray electric currents. Metal pipe corrosion is a continuous and variable process of ion release from the pipe into the water. ![]() Plastic and concrete pipes tend to be resistant to corrosion. Pipes used to distribute drinking water are made of plastic, concrete, or metal (e.g., steel, galvanized steel, ductile iron, copper, or aluminum). Causes of corrosion in water system pipes Fluorosilicates contribute to better water stability with less potential for corrosion, because silica stabilizes the pipe surface. Public Health Service for fluoridation of public water supplies (0.7 mg/L, or parts per million), the fluoride ion has little influence on either corrosion or on the amounts of corroded metals released into the water. The concern that using fluorosilicate additives to fluoridate drinking water causes water system pipes to corrode is not supported by science.
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