Classification of main source water type of drinking water plants

1 - Primarily surface water

'Primarily surface water' includes plants treating 90% or more surface water (water from sources open to the atmosphere such as rivers, lakes and reservoirs).

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

'Primarily groundwater and groundwater under the direct influence of surface water' includes plants treating 90% or more groundwater (water found in underground aquifers which supplies wells and springs) or groundwater under the direct influence of surface water (GUDI: groundwater supply sources under conditions where microbial pathogens are able to travel from surface water to the groundwater source).

3 - All other source water combinations