from Scripps Howard News Service During a drought, it may be tempting to give the lawn a daily sprinkling or water the vegetable garden for an hour each morning. Before you do, take note of how much water you will use consumptively.
"Consumptive use of water occurs when water is drawn from a ground or surface source and not directly returned to the earth," explains Al Jarrett, professor of agricultural engineering in Penn State's College of Agricultural Sciences. "It's a major concern during drought emergencies."
Consumptively used water doesn't disappear forever. It is released into the atmosphere through evaporation and transpiration. But it can be reused only when it returns to the earth as precipitation--and in a dry summer, that could take a while.
The water you sprinkle on your lawn and garden is used consumptively since it either evaporates or is taken up by the plants' roots. The 3.5 gallons of water used to flush the toilet or the 30 gallons used to wash a load of clothes is not used consumptively since it returns to the earth once it is treated.
"Not surprisingly, agriculture is one of the largest consumptive users of water," says Jarrett. "It requires an average 600,000 gallons of water each year to grow an acre of any crop. Except for the small amount that remains in the stems and leaves, all of this water is transpired into the air."
During a declared drought emergency, certain water uses may be restricted. Homeowners watering lawns and gardens also should monitor water consumption during a drought. Garden hoses, sprinklers and basin faucets use from three to five gallons per minute. If you run a sprinkler for two hours, that can amount to 600 gallons.
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