When we think of the amount of water needed to grow something, we usually only think of the water we use to irrigate a farm or water a garden. When we think of the water required for animals, we only think of the amount they drink, and maybe the amount used to wash them.
This water, the kind that comes from a spigot, is referred to as blue water. Blue water is taken from rivers, streams, lakes, ponds, and pumped up from underground aquifers.
But we also have to think about the water that rains down on plants and keeps the soil moist, that part of the rain that never flows into those sources of blue water. This rain water that never makes it to the river is vitally important to plant growth, and is referred to as green water.
When we think of animals, we need to consider not just the water they drink, but the water required to grow the food they eat as well.
Finally, we must consider the pollution caused by how we grow and make things. Grey water is the amount of pure water required to dilute these pollutants to safe levels.
Interested in actually assessing the water footprint of your products and supply chain? Check out the Water Footprint Assessment Manual, published by the Water Footprint Network.
Meg is an engineer with a BS in Physics from George Mason University and a MS in Product Development (combined Systems Engineering and Masters in Business Administration curriculum) from Naval Postgraduate School.