Artificial rain showers show how ground layers clean water
Approximately 60% of drinking water in the Netherlands is produced from groundwater. Groundwater is a clean source: it originates from surface water and precipitation that has percolated through the ground to reach the deeper layers. During the ground passage micro-organisms and chemical contaminants are filtered out of the water. KWR, within the water sector’s joint research programme (BTO), studies how the removal of viruses and bacteria occurs.
More knowledge about the effectiveness of ground passage clarifies the risks for drinking water
For water companies it is important to know how effectively the groundwater passage removes micro-organisms, particularly in the top, unsaturated layer. They use this information to design shallow groundwater catchment areas, but also to regulate recreational activities and grazing in these areas, since these activities may result in faecal pathogenic micro-organism transmission to the groundwater.
Modelling the risks
In 2013, a laboratory column set-up is designed and constructed, and filled with soil taken from a shallow water catchment area. Rainfall experiments with a model bacterium and a model virus are performed. Using sensors, soil moisture and pressure in the columns are monitored for hydrological characterization of the unsaturated conditions; the removal of micro-organisms is monitored through regular sampling. The results show that the largest portion of the pathogen removal takes place in the upper 50 cm of the unsaturated zone, which is the most unsaturated layer. With hydrological modelling of the unsaturated system and the microbial results, water companies can translate the collected research data to their own catchment areas.
© 2018 KWR Watercycle Research Institute
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Senior scientific researcher