The United States is fortunate to have ample water resources compared to many other countries around the world. Even still, water protection and conservation is important because water is limited and no place is immune from drought. Water use in the United States has dropped significantly over time through efficiency and conservation, but more must be done to ensure stable water supplies as climate change makes precipitation and weather conditions more volatile.
The United States has immense amounts of water. The country has an estimated 4.3 percent of the world’s population yet contains more than 7 percent of global renewable freshwater resources. It is home to the largest freshwater lake system in the world, the Great Lakes, which holds 6 quadrillion gallons of water (that’s a 6 followed by 15 zeros). And the mighty Mississippi River flows at 4.4 million gallons per second (16,792 cubic meters) at its mouth in New Orleans, which supplies water to about 15 million people along the way.
As vast as the United States’ water resources are, they are not endless. This water needs to be conserved and protected, especially given that the average American water footprint – or the total amount of water directly and indirectly consumed – is nearly twice the global average. Major water resources like the Colorado River and the Ogallala Aquifer that underlie parts of eight states in the High Plains consistently experience significantly decreased water levels because human demand has outpaced natural availability.
Droughts, which mean below average levels of precipitation, can happen anywhere and quickly diminish water supplies. For example, the historically severe US Drought of 2012 covered the majority of the country and caused many water-related problems, including major crop failures. In addition, climate change will continue to impact water supplies by altering precipitation patterns. In fact, a report by the Natural Resources Defense Council and Tetra Tech found that 70 percent of US counties could face water shortages by 2050 because of pressure from climate change, population increases and economic growth. Moreover, a GAO report found that water managers in 40 out of 50 states expect water shortages in the coming 10 years, regardless of drought conditions. All of this has major implications for how water is used in the United States.
Water Use in the United States
The United States Geological Survey (USGS) estimates that people in the US withdraw 322 billion gallons of water a day, including both fresh and saline water. (Note that these are 2015 numbers, the most recent year for which data is available.) The greatest portion of total withdrawals goes to thermoelectric power plants for cooling, with agriculture withdrawing somewhat lower volumes for crop irrigation. The third highest total amount of water goes to “public supply” (i.e., municipal and water company drinking water) which winds its way to be filtered at treatment systems each day. It’s worth stating that the treatment and movement of so much water requires massive amounts of energy, which in turn, requires massive amounts of water to produce that energy. See Table 1. below for more detail on water withdrawals by sector:
Table 1. Water Withdrawals in the United States by Sector
|SECTOR||TOTAL WITHDRAWALS (billion gallons per day)||PERCENT OF TOTAL WITHDRAWALS|
|Self-Supply Domestic (e.g., home water wells)||3.26||1|
A promising trend has emerged over the past 20 years or more with people and enterprises in the United States withdrawing and using less water. Since the previous USGS water report in 2010, the US has reduced its water withdrawals by 9 percent, which is the lowest recorded level in 45 years. Much of this is due to greater deployment of water and energy efficient fixtures, technologies and processes, yet much more must be done.
Water: Bringing it All Back Home
Most of the water that goes into a person’s house is for uses that don’t require as high level of purification, such as watering the lawn and flushing the toilet. Water that is not so contaminated can be reused as greywater for non-potable purposes as a means of wisely managing resources. The water withdrawn, some that runs through people’s showers and sinks, is potable, which means it is clean enough to drink. Water is also used for commercial and industrial purposes, for the production of the goods and services that people use daily. Clearly comprehensive water conservation goes beyond saving water at home.
In order to conserve great volumes of water, the country needs to conserve all the things that require water in their production, such as food that is eaten to clothes that are bought to energy that powers homes. This means changing the way water, wastewater and energy systems work, and changing the way people think about how water is used and consumed in everyday items and services.