Corrosion

Corrosion and Metals

CORROSION BACKGROUND

According to the Centers for Disease Control and Prevention Pipes used to distribute drinking water are made of plastic, concrete, or metal (e.g., steel, galvanized steel, ductile iron, copper, or aluminum). Plastic and concrete pipes tend to be resistant to corrosion. Metal pipe corrosion is a continuous and variable process of ion release from the pipe into the water. 

METALS BACKGROUND

According to the CDC All metals have slightly different properties, and galvanic differences are the tendency of one metal to release electrons to another metal. The galvanic series of metals is the hierarchy of which metals will release their electrons to other metals. Metals lower in the galvanic series more negatively charged will sacrifice their electrons to metals higher in the series. An example that many people are familiar with is zinc galvanizing of steel, where the zinc surface coating protects the steel from rusting. The galvanic interaction of different metals has a significant role in pipe corrosion, because many commercial metals are alloys of various metals. Therefore, the interior or exterior surfaces of the pipe can provide locations for an electrochemical cell which can start the process of pipe corrosion.

WHY TEST FOR CORROSION AND METALS?

Chemical additives are added to water during the water treatment process. More than 40 chemical additives can be used to treat drinking water. Many of these commonly used additives are acidic, such as ferric chloride and aluminum sulfate, which are added to remove turbidity and other particulate matter. Various chlorine disinfectants also act as acids and have the potential to reduce pH, alkalinity, and buffer intensity. These acidic water treatment additives can interfere with corrosion protection. The amounts of each of these other additives used in water treatment typically are 5 to 10 times the amount of the fluoride additive for fluoridation of drinking water; therefore, their potential effect on the factors affecting water corrosivity is proportionately greater.

SOURCES OF CORROSION

The CDC states 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. 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.

HEALTH CONCERNS

Corrosion can cause Copper and Lead contamination in your water.  When pipes corrode that allows Copper and lead to leach into your drinking water.  Lead contamination can lead to mental development problems in children as well as high blood pressure in adults.  Copper contamination could cause damage to your kidneys and liver over time as well as gastrointestinal problems.



REMEDIES

Water treatment can improve corrosion issues.
The following types of water treatment solutions are recommended:

Limestone chip filters
Soda ash feeds
Phosphate solution feeds
Silicate solution feeds
Oxygen scavengers
Coatings
Insulating unions
Click here to find a water treatment provider who can help solve corrosion issues. 

Click here to find products certified by WQA for the reduction of corrosion byproducts such as copper or lead (Certified to NSF/ANSI Standard 53 or 58).
Information provided by Water Quality Association 3.16.21

For more information check out the following links
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