Zinc Contamination in Drinking Water

Apparently zinc, due to galvanized pipe corrosion, is much more frequently present in drinking water than is commonly suspected. Aside from the question of possible deleteriousness there is an annoyance attaching to its presence in more than traces that is akin to the iron nuisance. Though not invariably done as a matter of uniform routine, this laboratory has made many hundreds of zinc determinations covering samples in connection with which such information seemed worth while. In many cases this was in consequence of complaints; in others, the test was made in connection with findings of large proportions of nitrites or free ammonia, it being frequently found that these are due to the reducing action of zinc on nitrate, in which case these data of course do not have the sanitary significance that would otherwise attach to them. Dissolved air, and particularly carbonic acid, such as is apt to be found in appreciable amounts in ground water sources, are prone to cause zinc solution. Especially is there apt to be this trouble with systems utilizing compressed air. Hard waters also attack zinc, and excessive chlorides or nitrates are practically sure to exert a pronounced corrosive effect.