This map indicates at which extraction sites nitrate has been found as a potential or current problem substance. The map is based on information from the area files for drinking water abstractions. Nitrate is a problem for groundwater abstractions, not for surface water abstractions. Nitrate mainly enters the groundwater via water that leaches from the root zone of agricultural soils. Nitrate can be broken down by denitrification. If pyrite oxidation occurs here, the sulphate content as well as the content of heavy metals, such as nickel, can also increase. This can also increase the hardness.
