24. How do I estimate the risk of groundwater pollution?

The risk of groundwater pollution can be estimated using the groundwater pollution risk estimation tool in the SFD Graphic Generator on the SFD web portal.  Risk in this case is a function of both the probability of pathogens from sanitation systems reaching groundwater and the probability of exposure to this hazard by people drinking that groundwater. The user is prompted to answer six questions in order to obtain an estimate of the risk of groundwater pollution.  Risk can be estimated for the city as a whole, or separately for different areas of the city. The tool provides a general estimate expressed as either ‘low’ or ‘significant’ risk, which can then be used to select appropriately from the SFD Selection Grid.

To assess risk of groundwater pollution you will need information on the:

  • Vulnerability of the aquifer
  • Lateral separation between sanitation systems and groundwater sources
  • Percentage of drinking water produced from groundwater sources
  • Water production technology used to extract groundwater

Remember to state clearly in the SFD Report the data used and any assumptions made.