Leaders of a small community water system in Florida inquired with specialists and Florida Gateway College about the origin of chlorides in source water.College representatives explained that the majority of chloride ions found in groundwater near the coast are of marine origin. Chloride ions can be introduced to groundwater through mixing with salt water, either as lateral intrusion from saline water bodies or as highly mineralized water up-coning from deeper aquifers.Sodium and chloride also occur in domestic wastewater, which means finding their source is important: Their presence may indicate nearby improper disposal of sewage. Elevated sodium and chloride must be
