Despite references to zinc throughout history beginning around 300 AD, German chemist Andreas Marggraf is generally given credit for the discovery of pure metallic zinc in 1746, heating a mixture of calamine and charcoal in a closed vessel. Chemically similar to magnesium, zinc is the 24th most abundant element in the Earth's crust and its many compounds are used in a variety of applications. Its major application as a pure metal is as corrosion-resistant plating on iron, but it is also used in the manufacture of batteries, castings, and alloys.
Zinc is a moderately reactive metal, its pure metal surface tarnishing quickly by forming a coating of zinc carbonate by the reaction with carbon dioxide in the air. Compounds of zinc are commonly used in dietary supplements, deodorants, anti-dandruff shampoos and luminescent paints.
Zinc is an essential nutrient for plants, animals, and humans and is the second most common trace metal in the human body after iron. Many diseases are linked to zinc deficiencies, particularly in the developing world, causing delayed growth, delayed sexual maturation, and susceptibility to infections.
Excess zinc intake, however, can cause issues such as ataxia (co-ordination, balance, and speech disorders), lethargy (sleepiness) and copper deficiency. The NHS advises the necessary zinc intake per day for men is about 9.5 mg for men and 7 mg for women which should be attainable from a normal daily diet. Dietary supplements containing zinc should be limited to 25 mg per day.
As well as naturally occurring in rocks and ores, it is possible for zinc to enter drinking water from industrial processes. This is uncommon in large quantities and most of the elevated zinc in drinking water can be traced to domestic plumbing fittings and pipes. These will regularly contain brass and water pipes can be made from galvanised steel which will leach zinc over time, most often in lower pH, soft water.
Public health bodies such as the WHO and DEFRA do not set legal limits for zinc in drinking water from a health perspective, but guidance is provided for elevated zinc that could cause undesirable tastes and appearances. The US EPA suggests a maximum level of 5 mg/L (ppm), above which an unpleasant metallic taste and greasy surface film can develop.
Zinc in your drinking water can be detected by the following tests.
Zinc can be reduced or removed from your drinking water using the following methods.
