GARDENERS FACTSHEET NO. 20
OCTOBER 1979
Revised Nov. 1994
A SIMPLE HOME DRIP IRRIGATION SYSTEM
Michael A. Ivie
Extension Agent-Agriculture
Illustrations: Gene Zegetosky, Extention Special Assistant
Since water is often a limiting factor for gardening in the
Virgin Islands, wise use of all available water is essential. We all
use water in our homes, and -much of this water is lost. GRAY
WATER is water that has been used for washing, and is no
longer fit for human consumption, but is not contaminated by
waste products. This water is often good for growing vegetables,
fruits or ornamentals. The problem is, how does the average
person collect, store, and utilize gray water without the major
expense of changing th e plumbing and building a gray water
cistern? The answer is simple, inexpensive, and requires little
construction. 
Any water system has 3 major parts. A source of water
(cistern), a pressurizing method (gravity or pumps), and a delivery
system (pipes and faucets). This drip irrigation system is no
exception, but is designed to be built with as little expense as
possible. THE CISTERN IS A PLASTIC GARBAGE CAN. It can
be any size or shape, depending on the amount of gray water you
produce and how often you produce it. The only major
requirement is that it be mosquito-proof. THE PRESSURE IS
PROVIDED BY GRAVITY. Simply place the cistern about 5 feet
above the area you wish to water.
THE DELIVERY SYSTEM is a commercially available drip
irrigation line and micro-tubing emitters. (Do not use other types
of emitters as gravity flow pressure works best with micro-
tubing). The drip irrigation line is a e” or ½” black plastic flexible
tube. Inserted into it through holes in the line, are tiny plastic
tubes called micro-tubing or “spaghetti-tubing”. (see Fig. 1)
These tubes are so small that only a drop of water comes
out at a time. This waters only the plant*s roots and wastes
almost no water by evaporation or over watering. A micro-tube
runs from the hose line to each plant.
To assemble your system you will need the following
materials and tools:
1.
Heavy duty PLASTIC GARBAGE-TYPE CONTAINER with
lid
2.
DRIP IRRIGATION LINE (enough to run from cistern to
opposite end of garden)
3.
MICRO-TUBING with end weights (I per plant)
4.
Female END FITTING with small screen (for end of drip
line)
5.
e” HOSE CLAMP
6.
PLASTIC SEALING COMPOUND
7.
Optional: CUT-OFF VALVE for drip line
8.
SHARP KNIFE
9.
SCREW DRIVER
10.
DRILL (Optional)
Before assembling the system, DECIDE ON THE
LOCATION of the cistern and garden. The cistern should be
close to the door so that filling it will be easy. The garden level
should be about 5 feet below the cistern, and not too far away.
The line running from the cistern to the garden must be covered
or buried to keep the water cool and to maximize the life of the
line. The garden area itself should be relatively level for uniform
watering to be achieved. The line should run within 18 inches of
all plants. After you have decided where to locate your cistern
and garden you can determine the amount of drip line you will
need. (see Fig. 2)
Products and suppliers mentioned by name in this publication are used as examples and in no way imply endorsement or recommendation of these products or suppliers.
Issued in furtherance of Cooperative Extension work, acts of Congress of May 8 and June 30, 1914 (as amended), in cooperation with the U.S. Department of Agriculture, D.S. Padda, Director, College of the Virgin Islands
Cooperative Extension Service. The College of the Virgin Islands Cooperative Extension Service is an Equal Opportunity/Affirmative Action organization, providing educational services in the field of agriculture, home economics,
rural development, 4-H youth development and related subjects to all persons regardless of race, color, religion, sex or national origin.
To assemble, PUNCH OR DRILL A HOLE on the side of the
cistern, about an inch above the bottom, to allow sludge to settle
without plugging the line. The hole should be a little smaller than
the drip line so that when it is pushed through, it fits tightly.
APPLYING SEALER around the junction makes it watertight. The
screened female END FITTING IS INSTALLED on the end of the
drip line inside the cistern so that the shoulder is flush with the
wall. (see Fig. 3)
Sealer applied around this fitting adds extra protection
against leaks. The drip line is then run to the garden area (always
in a down-hill direction), and buried along the way. The drip line
end is crimped over and the HOSE CLAMP TIGHTENED on it to
close the end. (see Fig. 4)
A MICRO-TUBING EMITTER IS INSTALLED for each
plant, following the instructions that come with it. Installation is
easy, and generally consists of punching a hole with a tool
(provided with the micro-tubing) and inserting one end of the
emitter into the drip line and running the other to the plant to be
watered. A weight on the end of the emitter keeps it in place. The
number of emitters is dependent on the number of plants your
water supply can support. For instance, figure a pint of water
twice weekly for a tomato plant. Use mulches to help “stretch”
the availability of this water (see Gardeners Factsheet #5)
The optional CUT-OFF VALVE can be installed in the drip
line near the cistern. (see Fig. 3). This is particularly advisable for
persons who produce a large amount of gray water only
occasionally, such as someone who washes clothes once a
week. The water can then be held over a long period, and
released a little each day.
Now that the system is installed where do you get the
water supply? While fresh water can be used in the system, most
people do not have sufficient supplies to use on plants. Water
from washing dishes is the most convenient source for gray
water systems. Just use dish pans and carry the cooled water to
the cistern instead of dumping it down the drain. Water from
automatic clothes washers can be used by attaching a garden
hose to the pump-out and running it to the cistern. When not in
use the hose is rolled up and tucked behind the washer. Wash
water with strong detergents should be diluted with rinse water
to lessen the possible build up of soil salts over a long period of
time. The use of low phosphate detergents is recommended.
When heavy amounts of chlorine bleach are used, leave the
cover off the cistern for a few hours before opening the valve.
The chlorine will then quickly evaporate and the water will be
safe to use. For the purist, showering while standing in a bucket
or wash basin will contribute, and can be the largest source of
gray water for those without a washing machine.
With ingenuity anyone, even those living on boats, can
save enough water for a few plants, while those with large
families can keep an entire garden going.
This type of system for 8 tomato plants can be built for
$10 - $15 and should last for 3 years, with care. Continued
staggered replacement of plants can assure a steady supply of
tomatoes, and soon pay for your system. Assuming 5 lbs. of
tomatoes per plant, and 3 plantings per year over 3 years you
could produce as much as 360 lbs. of tomatoes worth
approximately a dollar a pound retail. This savings on the food
budget is in addition to the generally higher quality of home
grown produce. Almost any type of plant can be grown with this
system, and different types can be mixed. Even ornamentals or
plants in pots can be watered this way.
To increase the convenience value of this type of system,
and to assure top yields, a balanced soluble fertilizer can be
added to the water in the cistern so the plants are continually
and easily fed. Look for a soluble fertilizer such as 10-10-10 or 20-
20-20 and follow the instructions on the package.
A gray water drip irrigation system is easy and inexpensive
to build, saves precious water, is convenient to use, and helps
your garden produce more money-saving homegrown
vegetables.