Facts and Reasoning: Water Scarcity

Promise Of Water Is Not Cheap

1 The water authority’s 30-year contract with Poseidon illustrates both the promise and peril of this water source. San Diego County agreed to pay for 48,000 acre-feet of water from the plant every year — whether it needs the water or not — to ensure a guaranteed supply. The water will cost $2,257 per acre-foot, about double the price of the authority’s most expensive supply now.

2 One acre-foot is enough to serve two average homes for a year. At a total output of 56,000 acre-feet, the plant would meet 7 percent of San Diego County’s annual water demand.

3 Many conservation groups are critical of desalination. They argue that it comes not only with high costs, but with a lot of environmental risks as well.

4 “If you look at our choices based on costs and (environmental) impacts," desalination "should always be at the bottom of that list,” environmentalist Conner Everts said. “It’s kind of an engineer’s dream, but there’s a lot of challenges to it.”

5 One of the big challenges is energy demand. Desalination requires more electricity than nearly any other water source, because water must be forced through reverse-osmosis membranes by high-pressure pumps. The amount of electricity needed drives up the cost of the water steeply. However, the San Diego County Water Authority expects the cost of imported water to rise over time, to a level where there would no longer be a price difference.