Where Does our Water Come From?

 Did you know that less than 1% of the water on this earth is available for all the humans, plants, and animals that live on land? Many people know that this small freshwater supply is part of a cycle known as the “hydrologic cycle.”

In the hydrologic cycle, rain, or snow falls. Then it runs off into lakes and streams or seeps into the ground. Some groundwater is taken up by trees and other vegetation and is returned back to the atmosphere by a process known as transpiration. Water is also returned to the atmosphere when it evaporates from ground, lake, or stream surfaces.  

Precipitation that does not seep into the ground becomes runoff that travels down a slope to combine with other draining water. These natural flows of stormwater go into ditches, then creeks, and on to rivers, which move the water out of the area. These drainage areas are known as watersheds, and we all live in a watershed! As water flows through a watershed, it can pick up contaminants that will negatively affect its quality.

Keeping our Water Clean 

To get a better picture of water quality, imagine this– if everyone in the world has one cup of water and each person adds a pinch of salt to that water, it may still be drinkable.  However, if a pinch of salt is added to that cup everyday, soon it would be too salty to drink. And even if we set that cup of water out to evaporate (to re-enter the hydrologic cycle), the next time rain fell back into the cup, it would get contaminated again by the salt left there—and we still couldn’t drink it! Groundwater and surface waters in lakes, man-made reservoirs, and rivers are similar to cups in that the water may go up and then come back down, but the contaminants stay and continue to build up. Eventually, our water becomes so contaminated it must be cleaned up by special equipment or treatment processes.

 Underground and surface water in our watersheds can pick up contaminates in many ways. Broken or poorly functioning septic systems, pesticides and fertilizers improperly applied to our yards, leaking underground storage tanks of gasoline, used oil, manure, and other household wastes can all contribute to poor water quality. In addition, cement and land surfaces that don’t absorb water can often speed up the rate at which water travels across it which can often cause erosion, flooding, and pollution problems in our towns and on our farms.

 Unfortunately, plants and animals can’t clean up their water and, as a result, contaminants can adversely affect the health of the community or “ecosystem” in which they live. As with our watersheds, we all live in an ecosystem--and a healthy ecosystem is important to the health of our communities.