Saline Water Use in the United States

In today's world we are all more aware of the need to conserve freshwater. With the ever-growing demand for water by growing populations worldwide, it makes sense to try to find more uses for the abundant saline water supplies that exist, mainly in the oceans. As these pie charts of the Nation's water use show, about 15 percent of all water used in the United States in 2005 was saline. (All 2005 water use information is from the report Estimated use of water in the United States in 2005.) The second chart shows that almost all saline withdrawals, over 95 percent, was used by the thermoelectric-power industry to cool electricity-generating equipment. About five percent of the Nation's saline water was used for mining and industrial purposes (For 2000, mining data was compiled only for the 22 States that reported significant withdrawals in 1995).

What is saline water?

Water that is saline contains significant amounts (referred to as "concentrations") of dissolved salts, the most common being the salt we all know so well—sodium chloride (NaCl). In this case, the concentration is the amount (by weight) of salt in water, as expressed in "parts per million" (ppm). If water has a concentration of 10,000 ppm of dissolved salts, then one percent (10,000 divided by 1,000,000) of the weight of the water comes from dissolved salts.

Here are our parameters for saline water:

• Fresh water - Less than 1,000 ppm
• Slightly saline water - From 1,000 ppm to 3,000 ppm
• Moderately saline water - From 3,000 ppm to 10,000 ppm
• Highly saline water - From 10,000 ppm to 35,000 ppm

Saline-water withdrawals by category of use, 2005

Saline water withdrawals by State, 2005

It makes sense that the states that border the Atlantic and Pacific Oceans, and the Gulf of Mexico should make the most use of saline water. This pie chart shows the states that used the most saline water in 2005—they are all coastal states. Almost one-half of all saline water used occurred in California, Florida, and Maryland. The main use was to cool electricity generators in power plants.

 Data table: Saline-water withdrawals by water-use category, 2005 (PDF)

Trends in saline-water withdrawals, 1950-2005

As the chart below shows, the use of saline water, and freshwater, also, has been trending downward since peaking in 1980. But, in the period of 1950 to 1980, the use of saline water increased at a much higher rate than freshwater use.

Total water use, 2000

• Estimated Use of Water in the United States in 2000, USGS Circular 1268:
• Surface-water withdrawals, 2000: Summary | Data table, by State | National maps
• Groundwater withdrawals, 2000: Summary | Data table, by State | National maps