For the gardener, summer droughts
can really be disheartening. One is left
with the choice of watching plants wilt or using whatever water is quickly
available (i.e. tap water or using water from your home’s well). Another, and arguably best, solution is to
harvest natural rain water. There are
several key advantages of using rain water, especially on food crops. If you are on a municipal water system, your
supply has had chlorine and probably fluoride added. If your home is on a well, a high mineral
content is possible. Also, when the
annual “dry spell” comes many cities turn to water restrictions—resulting in
fines if someone is caught watering lawns, gardens, or washing vehicles. Of equal importance, a drought, by nature, puts
a strain on a home’s well. This is only
compounded if large quantities of well water are used to sustain a size-able
garden. 
My rain barrel systems consists of
three 55 gallon barrels all connected together at the bottom so the water level
stays the same in all, regardless from which I chose to draw water. I decided it was best to pour a concrete slab
for them as well. Water is heavy. Each gallon weighs 8.34 lbs. When full, the system contains roughly 160
gallons, which is a total weight of over 1,300 pounds! A slab ensures they won’t begin to lean,
tilt, or begin to sink into the ground as time goes by. The rightmost barrel (the black one) is
filled from the gutter’s downspout via a diverter made by Rainreserve, found here. I chose this particular diverter because it
fit neatly inline with the downspout and, when installed level with the
barrel’s inlet, the excess water flows on down the same gutter when all three
barrels are full, thus, eliminating the need for separate overflow piping. I keep lids on all the barrels to prevent
evaporation and help keep bugs, leaves, etc. out of the water supply. Since the lids seal tightly, I drilled three small
vent holes in the front of each barrel about two inches down from the top. Without the vents, air pressure would build
inside and interfere with filling during a hard rain. 
So, how much water does the prudent
gardener need to try collect? No
set-in-stone answer exists, but a bit of math will help guide us. The total area of my raised beds is 72 square
feet. If I want to give them the
equivalent of ½ “ of rain, I multiply 72 times 144 (this converts square feet
into square inches) and I get 10,368 sq.in.
This multiplies by the amount of rain I want to duplicate, in this
example ½”. The result is 5,184—this number
is cubic inches of water. We then divide
5,184 by 231 (one gallon = 231 cubic inches) and we arrive at 22.4
gallons. This tells me that in order to
emulate ½” of rain on the 72 sq.ft. of my raised beds, I will need to use 22.4
gallons. Since my system holds about 160
gallons, I can use 22.4 gallons just over seven times until the barrels are
empty. What does all that mean? Assuming I water every other day, I can
sustain my gardens with the equivalent of ½” of rain, at each watering, for a
full 14 days without a drop of water falling from the sky. 
The styles and processes of
collecting rain water are plentiful.
Some systems are elevated to create a gravity fed scenario which allows
a garden hose to be attached and the water naturally flows to its
destination. I set mine up to
intentionally give me the exercise of carrying water to the gardens.
One last note; rain water is
“soft”. That is to say it doesn’t
contain calcium, magnesium and other minerals.
If you have ever looked into making your own lye soap, you’ll know it
requires soft water—your rain water is the perfect source.
Have Questions? Find me on Facebook. - Mark
Mark Dula is from Hudson North Carolina, where he is a drafting and
AutoCAD instructor. Mark is also a graduate of Appalachian State
University and spends probably more time than advisable with my friend
Kurt.
Yw city! We hope its useful.
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