Water Education - Water and Health

Understand Galvanized Water Pipes

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corroded pipe

Do you know what your water pipe is made of and how safe it is? Although galvanized (zinc-coated) pipe is still considered to be a safe transport material for drinking water, there are some potential health concerns if the water supply is corrosive due to its acidic condition (low pH). Public water supplies treat their water to make it essentially non-corrosive—so this should not be a concern if you are on a public water system. The concern is not for zinc or iron that may be leaching from the pipe, but for lead and especially cadmium, the two other heavy metals that may be present as impurities in the zinc used for the galvanizing process.

The primary drinking water standards for lead and cadmium are 0.015 and 0.005 mg/L, respectively. If you are on a private well water system where the plumbing is galvanized pipe and the water frequently has a slightly bitter taste, you should have your water tested. Private well is at a high risk of being contaminated. A zinc concentration of more than 5 mg/L will give water a bitter astringent taste but is not a health risk. The EPA has set a secondary contaminant level of 5 mg/L for zinc because of how it affects taste.

Analysis and treatment of the contaminants include many factors that contribute to corrosion and the leaching of contaminants from drinking water distribution systems. The principal factors are the type of materials used, the age of the plumbing system, the stagnation time of the water, and the quality of the water in the system, including the pH value. Metal leaching will be affected differently by each of these factors. Using lead as a trigger to initiate corrosion control programs in a drinking water distribution system, activity levels have been developed for both residential and non-residential buildings.

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