Health Can make brown tap water sick?

Brown water: low nitrate levels problematic in some places

While it is well known that our waterworks have a regionally high nitrate level, for some time now a completely new problem has arisen elsewhere: too little nitrate. The decline in industrial emissions has already put many regions near pre-industrial levels in terms of nitrogen content in the air and in the soil.

According to the Helmholtz Center for Environmental Research (UFZ), brown water in drinking water production is often reported as a problem, especially in semi-natural catchment areas with a lot of forest dams. Investigations have now shown that this is due to low levels of reactive nitrogen in the atmosphere, so that in Auenböden and tributaries to the dams. Sometimes the nitrate levels are below 6 mg / liter of water. So far below the limit of 50 mg, which is exceeded in some places by excessive manure entries and also makes problems in the water treatment.

But why is not enough nitrate good too? This is pure chemistry and the soil in the floodplains is the laboratory: Here, free carbon, phosphate and some metals are bound to iron compounds in the soil. Low nitrate levels allow chemical reduction of these compounds with the result that carbon, phosphate and some metals are washed out. They are partly responsible for the brown coloration and partly for increased growth of algae. Both are not worrying for the consumer, but the cost of drinking water treatment rise, so the scientists. The study, funded by the Federal Ministry of Education and Research, should now be the basis for future experiments, from which concrete measures for problem solving should be derived. Friederike Heidenhof, aid