Consumptive Use

While nearly all water used indoors can be recycled, water used outside usually cannot because of evaporation. This also is known as "consumptive use."

Consumptive use is the water that is actually consumed and not returned to the immediate water environment. It is the portion of water that evaporates, is used in products or crops, or consumed by humans or livestock.

Why reducing consumptive use is important

In 1928, the Boulder Canyon Project Act determined the distribution of water to Colorado, New Mexico, Utah, Wyoming, Arizona, California and Nevada. The compact limited Nevada's allocation to 300,000 acre-feet of water per year.

The Bureau of Reclamation, which is responsible for keeping track of Colorado River water, deducts any returned water (return-flow credits) from Nevada's river withdrawals. Consumptive use water, such as landscape watering, does not earn the valley any return-flow credits because the water is not returned to the system.

Southern Nevada's water use is based on "net" consumption rather than "gross" withdrawals. Because Southern Nevada returns about 200,000 acre-feet of water to the Colorado River system each year, it receives about 200,000 acre-feet of return-flow credits. This allows us to withdraw nearly 500,000 acre-feet of water each year, stretching our original allocation.

Save water where it counts

Approximately 60 percent of Southern Nevada's water is used outdoors. This "consumed" water does not provide the Las Vegas Valley with any return-flow credits and is counted against our Colorado River withdrawals.

Because Nevada does not receive water credits for water used outdoors, the conservation programs of the Southern Nevada Water Authority (SNWA) focus on reducing outdoor water uses such as landscape watering.

The fact is, Southern Nevada's water consumption is all about landscape watering. In other words, the water we use inside our homes, businesses and even hotel rooms has much less impact on our community's water supply than the water used outside. That's not to say that water should be left running while brushing your teeth or shaving. But the way to really make a difference is to save water where it counts the most--outside. SNWA has put in place a number of programs and rebates to help Southern Nevadans achieve conservation goals.