Multi Barrier System: The key to ensuring clean, safe and reliable drinking water is to understand the drinking water supply from the source all the way to the consumer’s tap. This knowledge includes understanding the general characteristics of the water and the land surrounding the water source, as well as mapping all the real and potential threats to the water quality. These threats can be natural, such as seasonal droughts or flooding, or created by human activity, such as agriculture, industrial practices, or recreational activities in the watershed. Threats can also arise in the treatment plant or distribution system thanks to operational breakdowns or aging infrastructure.

The multi-barrier approach takes all of these threats into account and makes sure there are “barriers” in place to either eliminate them or minimize their impact. It includes selecting the best available source (e.g., lake, river, aquifer) and protecting it from contamination, using effective water treatment, and preventing water quality deterioration in the distribution system.

The approach recognizes that while each individual barrier may be not be able to completely remove or prevent contamination, and therefore protect public health, together the barriers work to provide greater assurance that the water will be safe to drink over the long term.