What is zinc?
Zinc is a metal with a white-blue shimmer that occurs primarily as ore (e.g. zinc sulphide ore, zinc blende, zinc spar). As zinc has the property of forming a weather-resistant protective layer (zinc oxide and carbonate) when exposed to air, it is used as corrosion protection. Along with the toxic elements mercury and cadmium, zinc forms the 12th group in the periodic table without being harmful.
Most of the zinc produced in metallurgy is used for galvanising iron and steel products. They are provided with a coating of zinc. Zinc compounds are used in many ways in the industry; for example, as a component of inexpensive, environmentally friendly batteries, paints and fertilisers. In the pharmaceutical industry, zinc is used in wound and care ointments. Zinc sheets (titanium zinc) are valued as high-quality and aesthetic materials in the building industry. For the outer skin of buildings, they are used as facade cladding, roofing, gutters, downpipes, cornices and window sills. When professionally processed by the plumbing trade, they are durable and maintenance-free.
How does zinc get into drinking water?
Zinc is naturally present in seawater, rivers and lakes. The current UK Drinking Water Ordinance has a limit value of 5 mg/l. Since conspicuous values in groundwater are not of geogenic origin, the reasons lie in environmental pollution from industrial wastewater, inadequate safety precautions at landfills, and zinc leaching from galvanised materials, pipes and roofing materials made of zinc sheeting. The advantage of corrosion protection is reversed, as the element is triggered by water with a low pH value, i.e. acidic character, and leaches out. Zinc emissions have industrial causes and enter the water cycle via rainwater and wastewater.
How does zinc affect the human body?
For humans, zinc is a vital substance that is absorbed with food. Since zinc cannot be stored in the body, it must be constantly supplied. Only part of the zinc is utilised, so the daily recommendation varies.
The WHO, the World Health Organisation, advises men to take 15mg and women 12mg. The enzymes of the energy, carbohydrate and fat metabolism, the sex and thyroid hormones, the immune system, insulin synthesis and many other areas of the organism are activated by the mineral. Zinc has a favourable influence on the harmful effects of cadmium and lead.
Zinc deficiency is caused by high copper or iron levels in the body, as both block zinc absorption. An extreme overdose (150 times the daily requirement) manifests in nausea, vomiting, abdominal pain and diarrhoea. No harmful effects on health can be assumed from drinking water containing zinc.
Drinking water polluted by zinc: What to do?
The Drinking Water Ordinance specifies a guideline value of 5 mg/l for the zinc content and thus complies with the WHO’s requirement. Zinc salts in more significant concentrations are responsible for turbidity and an unpleasant taste in the water.
Zinc is phytotoxic, i.e. it is toxic to plants to a certain degree. Therefore, the Sewage Sludge Ordinance states that the maximum zinc concentration in sewage sludge applied to agricultural, forestry and horticultural land must not exceed 3 grams per kilo of dry matter. One of the methods used in wastewater treatment is coagulation. This process chemically causes flocculation of the colloids. The resulting flocculent zinc aggregates are large enough to be separated from the water in a second step.
Get zinc concentration tested
The waterworks’ guarantee of safe drinking water ends at the house connection. The drinking water passes through the domestic installation from there to the tap. This often means galvanised iron pipes, copper pipes, and sometimes even outdated lead pipes. This may provide ample opportunity to release zinc, iron, copper, or lead.
In addition to these contaminants, other pollutants, such as microbes, can also pollute tap water. Since bacteria and heavy metals are invisible, only a laboratory water test can provide reliable findings. A water test examines the substances of your own water.