Protection of groundwater against microbial contamination

A novel microbial risk analysis of groundwater as part of the Dutch guideline document for Quantitative Microbial Risk Assessment (QMRA) of drinking water consumption encompasses 1) vulnerability assessment of groundwater production sites, 2) calculating the protection zone against microbial contamination to remain below an infection risk of 1/10,000 persons/year, 3)  assessment of contamination sources within the protection zone, and 4) QMRA for identified contamination sources. Protection zones are based on a standard virus contamination scenario and may be computed using a required minimal travel time, a hydrological model that includes a first order decay term for virus inactivation and attachment, or the computational tool QMRAwell. QMRAwell is designed for unconfined and (semi)confined sandy aquifers with a forced groundwater gradient due to pumping. QMRAwell can also be used to conduct  QMRA.