Water Problems

Does city water require further treatment before being used in electro-plating?


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Q. I am employed by a manufacturing company that is bringing a small electro-plating setup in-house. I have been asked to help with the design of the facility, specifically in the area of water usage and quality. I have reviewed my specifications for water treatment with my boss, who believes city water will be adequate for the various plating and rinsing tanks. I, on the other hand, think that the incoming water requires further treatment before being used. Can you give me some ammunition to use in my next discussion with my boss?—J.M.

A. City water, while being acceptable for human consumption, contains small amounts of impurities that are harmful to plating baths and rinsing operations. What can be found in city water? Dissolved minerals, for example. Depending on the area in which you are located, the water will contain varying amounts of iron, calcium and magnesium-based salts. The calcium and magnesium-based salts account for most of the so-called “hardness” of water. As these materials build up in your plating bath, they may form a fine precipitate and will most likely cause roughness.

Staining is another by-product of hard water. Municipal water supplies may be treated with chlorine to reduce bacteria and algae growth. During certain times of the year the bacterial and algae “load” in water will increase, and additional chlorine must be used to control these organ-isms. The result is great amounts of residual chlorine in the water. The chlorine can and does affect your plating baths.

Get a water analysis from you local water supplier to find out what your local water contains. Compare the numbers with those you are proposing for use in the plant. This should give you some “ammo” for your next discussion with your boss.