Classification of main source water type of drinking water plants

• 2 - Primarily groundwater and groundwater under the direct influence of surface water (GUDI)

2.2 - Primarily groundwater under the direct influence of surface water (GUDI)

'Primarily groundwater under the direct influence of surface water' includes plants treating 90% or more groundwater supply sources under conditions where microbial pathogens are able to travel from surface water to the groundwater source.