Saving Water: Part 1

Comparing the earth to a spaceship is especially appropriate in the case of water. All of the water needed for a journey through space would have to be loaded on board at the beginning of the trip. There would be no way to manufacture additional water once the ship was in orbit. The water would have to be used over and over again.

In exactly the same way, the supply of water on earth is constant, and it’s over four billion years old. The system by which water is continuously circulated through the biosphere is called the hydrologic cycle. Evaporation and transpiration (the emission of water vapor from plants) are the mechanisms that redistribute water. Water vapor collects in clouds, condenses, and then falls again to earth. There it is re-evaporated and re-transpired, only to fall once more as precipitation.

If the supply of water is constant, if it will always be here, you might ask why we need to worry about conserving it. There are two good reasons. First, while we are not about to run out of water, we are already running out of inexpensive water. Think of what had to happen before you could turn on a faucet and get water. People had to located a source of water; then they had to build aqueducts, canals, water tunnels, and pipes to carry it, machines to pump it, and plants to treat it. To carry away used water, they have had to build drains and sewers, and more plants to treat the water before it’ s discharged into a stream, lake, or ocean.

Providing water is costly, and the cost is not just monetary. For example, the once majestic Colorado River, the only significant source of surface water in the southwestern United States, has been so transformed by dams and canals, pipelines, and reservoirs that it is now little more than a vast, controlled plumbing system. By the time the 1,400-mile-long (2,240 km) river reaches Mexico, it is not much more than a creek. There, a final dam, the Morelos, diverts for irrigation what little water remains, so that by the time the river reaches the sea, it is dry. This Colorado River is a far cry from that seen by the Spanish explorer Hernando de Alarcon, who in 1540 journeyed up the river from the Gulf of California and described it as, “… A very mighty river, which ran so great a fury of a storm that we could hardly rail against it.”