Summary:
By collecting rain from a roof during rain
events and storing it in a barrel or cistern, homeowners can create an
alternative
water supply to irrigate their home gardens and
landscaping that will not overpump the groundwater or increase the water
bill.
In this example, a typical home garden would be 400
ft2 on which the homeowner plans to irrigate using a 55-gal
heavy-duty plastic barrel with a spigot located near the bottom of
the tank. The objective of this study was to
develop a spreadsheet-based model using daily data to determine how the
watering
habits of home gardeners affect the amount of
available supplemental irrigation water and cost savings using a typical
55-gal
rain barrel, thus resulting in a more realistic
cost-benefit analysis. The model allows for multiple, user-selected
criteria
such as the size of the barrel, number of barrels,
harvest efficiency of the guttering system, size of the garden, the
catchment
area, and the watering habits of the homeowner
(such as how many days without precipitation have occurred before they
feel
the need to water), which were used to develop
seven different scenarios. To optimize rainwater use and cost benefits,
the
following parameters are recommended: catchment
area of 600 ft2, 90% harvest efficiency by reducing leaks and
other problems with guttering and rain barrel, threshold of 0.10 inch
for a
wet day, minimum of only 2 dry days before using
the water in the barrel, and one overflow barrel. In this case, a
homeowner
in Knoxville, TN, can harvest an average of 1,570
gal per season (range of 1,076–2,076 gal), at an average cost savings of
$22,
and thus recover the cost of the two barrels in 3–6
years.