The sources of drinking water (both tap and bottled water) include rivers, lakes, streams, ponds, reservoirs, springs and wells. As water travels over the surface of the land or through the ground, it dissolves naturally-occurring minerals and, in some cases, radioactive material, and can pick up substances resulting from the presence of animals or from human activity.

Lake Erie, a surface water source, is the source of drinking water for the greater Cleveland area. Lake Erie is a part of the Great Lakes system that also includes Lakes Superior, Michigan, Huron and Ontario. An assessment of Lake Erie as a source of drinking water will soon be completed under the direction of the Ohio EPA.