The relative safety of Hawaii's drinking water

There are two types of drinking water sources: groundwater and surface water (the latter includes catchment of rain). Surface water runs over the surface of the earth in rivers and watercourses, or is stored in lakes and reservoirs. groundwater is water that is stored below ground level; it feeds artesian wells and springs. It is important to remember that untreated groundwater may not be the same thing as treated drinking water. A contaminant in groundwater represents a threat to a drinking water source but not necessarily a threat to health, if the contaminant's concentration is decreased before it becomes available as potable.