How does nitrate get into groundwater?

Groundwater resources located below agricultural areas are exposed to the greatest contamination by nitrates. Around 74 percent of German drinking water comes from groundwater. Water protection in Germany has been criticizing intensive soil use and the associated use of nitrogen-containing fertilizers for some time.

But it's not just manure that poses a problem in agriculture: artificial fertilizer and inadequately sealed silos cause high nitrate concentrations in the groundwater. So-called fermentation residues from biogas plants also have a high nitrate content. These residues, in turn, also end up on German fields.

Plant organisms can use the fertilized nitrogen salts in a positive sense, but an excess of nitrates is no longer utilized by the plants. The nitrates therefore accumulate in the soil. Precipitation such as rain or melting snow then ensures that the salts seep into deeper regions of the ground. The precipitation, which is now contaminated with nitrates, ends up in the groundwater. Excess nitrogen salts also end up in lakes, rivers and other bodies of water in the same way.

Depending on the region, domestic water is obtained from surface or spring water, but usually from groundwater. The high concentration of nitrogen salts represents a serious problem for the water treatment companies. The removal of nitrates cannot be achieved 100 percent, while even the smallest amounts pose a real threat, especially to infants.