What’s the difference between ground water and surface water? Is one safer than the other?

Water is generally classified into two groups: Surface Water and Ground Water.

Surface water is just what the name implies: it is water found in a river, lake or a superficial cavity of some kind, including dug wells. Surface water is exposed to many different contaminants, such as animal wastes, pesticides, insecticides, industrial wastes, algae and many other organic materials. Even surface water found in a pristine mountain stream possibly contains giardia or coliform bacteria from the feces of wild animals, and should be boiled or disinfected by some means prior to using it. Many residents of Vancouver Island have dug wells that they’ve been using without incident, but as our area becomes denser in populations, the risk of contamination grows. We can treat ground water with an ultra-violet filter that uses light to kill off harmful bacteria.


Ground Water is that which is trapped beneath the ground. Rain that soaks into the ground, rivers that disappear beneath the earth, melting snow are but a few of the sources that recharge the supply of underground water. Because of the many sources of recharge, ground water may contain any or all of the contaminants found in surface water as well as the dissolved minerals it picks up during its long stay underground. Waters that contains dissolved minerals, such as calcium and magnesium above certain levels are considered "hard water".