The state of the U.S. water supply

Key Concepts

• U.S. demand for fresh water is relatively static. Per capita water use has declined since the 1970s (largely because of increasing efficiencies in how water is used to cool power plants, which accounts for about half of all U.S. fresh water withdrawals), but a growing population means our overall demand for fresh water has stayed consistent for decades.
• U.S. fresh water availability differs greatly between eastern and western states. The 100th meridian creates a natural divide between the arid and increasingly water-depleted West from the water-rich East, but that dividing line may be shifting eastward as climate change alters precipitation patterns.
• The sources and nature of U.S. water pollution have changed in recent decades. A few decades ago, the vast majority of U.S. water pollution came from single identifiable sources such as factories and power plants. Today, due largely to regulation of those “point” sources, the majority of water pollution originates from “non-point” sources such as agricultural and urban runoff and sediment from soil erosion—sources difficult to regulate given the diffuse and widespread nature of the pollution.

A Few Facts to Know

• Less than 3% of the Earth’s water is fresh and two-thirds of that is frozen, leaving less than 1% accessible for human use in groundwater, lakes, rivers, and streams.
• People consume only 1-3% of water that’s been treated for safe consumption in the United States; most is used in applications where such a high degree of water quality is not necessary (e.g., laundry, showers, and watering lawns).
• The majority (85%) of U.S. fresh water consumption is for irrigation and livestock.
• Not all water withdrawn from waterways is “consumed” (meaning unavailable for immediate reuse). Water withdrawn for cooling thermal power plans, for example, is returned to the watershed (albeit warmer).
• Reclaimed water, which is water treated at wastewater treatment facilities for secondary uses, can increase water availability and sustainability for cities and regions facing water scarcity.
• Environmental Protection Agency (EPA) regulations help ensure our drinking water is safe (although enforcement and compliance varies from place to place, and violations in economically depressed areas are in many cases less aggressively addressed). But scores of known contaminants are simply not regulated by EPA. Neither are private wells, which are the source of fresh water for about 13 million U.S. households.
• Climate models predict a general increase in water shortages in the U.S. West in decades ahead, and seasonal shortages have already led to politically sensitive mandatory agricultural and residential water-use restrictions in some western states.
• Desalination is one solution to water shortage issues – an expensive one – and disposing of the brine that’s left behind can cause ecological damage.

This page is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License. License applies to text and video only. Journalists are free to use any text or video on this page with or without attribution to SciLine.