Q What is water scarcity, and how do our daily habits contribute to it?
— Sarah Marquardt, Madison, Wis.
A Trina McMahon, professor in the departments of civil and environmental engineering and bacteriology at the University of Wisconsin-Madison:
Water scarcity is essentially when there’s not enough water in the right place at the right time. Even in places such as states next to the Great Lakes, the largest source of fresh water in the world, water may not always be where it’s needed or may not be clean enough for its intended purposes.
There are established technologies for treating water for drinking and for treating wastewater. If the water that you start with has a lot of chemicals or pathogens in it, then it takes a lot more money and energy to make the water clean enough to drink.
Many areas get their drinking water from groundwater. Water is pumped out of very deep aquifers, areas underground that hold water like a giant sponge in the earth. The water from the aquifers is very clean so it doesn’t require much treatment.
After we use that water and release it back to the environment, it goes into surface water like a lake or a river. We’ve taken water out of the ground and put it on the surface.
The replenishment of the ground water is a very slow and long process, so we run the risk of the groundwater being depleted or the level of the water going down.
Water is a finite resource because the rate at which the water gets put back into the aquifer by natural processes is very slow. Using less water on a daily basis will make that aquifer last longer for future generations.
Climate change is a threat to both local and global water systems, as it’s altering the water cycle. That can mean more rain as well as rain that’s coming in more intense, flash events.
Where water is being taken from lakes and rivers, the intense rain can influence the quantity and quality of the water that’s available. There are also lots of other issues related to the pollution of surface waters that are exacerbated by climate change drivers.