Surface water (streams, rivers and lakes) or groundwater (aquiferHelpaquiferA natural underground layer, often made of sand or gravel, which contains water) can serve as a source of drinking water, called source water. The water source provides water for public drinking water supplies and private water wells. Public services treat most of the water used for public drinking water supply. Protecting source water from contamination can reduce treatment costs. Protecting source water also reduces risks to public health due to exposure to contaminated water.
Source Water Protection is protecting source water (including water from lakes, rivers and underground aquifers) from overuse and pollution. The protection of water sources is part of a multi-barrier approach to protecting municipal sources of drinking water that was recommended by Canadian Judge Dennis O'Connor in his Walkerton reports. This study was launched in 2002 in response to the Walkerton Tragedy, in which the city of Walkerton, Ontario's drinking water was contaminated with E. coli bacteria.