Community water systems are classified based on the presence of certain source types (i.e. any surface water, or any groundwater influenced by surface water). The primary water source of a community water system indicates the presence of a source type that determines the treatment and filtration requirements for that system. Because surface water and groundwater are treated differently, the primary water source type classification by state and federal agencies allows for higher monitoring and fulfills greater public health protection requirements.
State and federal drinking water system databases define six categories of primary water sources: 1. groundwater under the direct influence of surface water; 2. purchased groundwater under the direct influence of surface water; 3. groundwater; 4. purchased groundwater; 5. surface water; and 6. purchased surface water (view full definition).