By Skip Richter
I don’t have a crystal ball, but there are a few things
which I can be quite sure of when it comes to the
future. Texas summers are going to be hot, and mostly
dry. Our population is rising and the quantity of
available water is not. So more laws and ordinances will
be passed in the years to come, further restricting how
and when water is used. And, the price of water will go
This means that more efficient watering systems will be
an important part of our landscapes. In fact they
already are. We have had the technology to get more out
of every drop of water we apply to gardens and
landscapes for decades now, but like many good ideas,
for one reason or another this technology just hasn’t
fully caught on. While there are several great gadgets
and techniques that will help us get the most out of our
watering dollar, in this article I want to focus on drip
I’ll bet every reader has heard of drip irrigation and
even understands how it works. I’ll also bet that most
readers don’t have a drip system in their garden or
landscape. Well, I understand. I was a late adapter
myself. Perhaps we feel the cost is prohibitive, maybe
we are intimidated by what seems too technical for the
average do-it-yourselfer, or we may just not be
convinced that it really works. Well, it’s not, it
isn’t, and it does! Read on and I’ll explain.
Why Drip Irrigation?
Drip irrigation is quite simple. It basically involves
delivering water to various parts of the landscape
through a series of plastic tubes and applying it right
where you want it through emitters that slowly apply it
onto the soil surface.
Drip offers a number of advantages over sprinkler
irrigation. It is an efficient way to water. More than
90 percent of the water you apply through drip
irrigation will be available to plants compared to only
50 to 60 percent with sprinklers.
A drip irrigation line applies water directly to the
soil rather than slinging it through the air and onto
the foliage where much is lost to evaporation.
Sprinklers wet the entire garden area so walkways and
areas between the plant rows get wet, too. This
off-target watering wastes water and increases weed
problems. You can walk through your garden while
irrigating with drip and have no muddy pathways. In
fact, I like to work in the garden while my drip system
is running. It’s kinda cool to watch!
Because water is applied slowly with drip, it is able to
move into the root zone without runoff and the soil
surface is not subject to erosion or crusting as with
sprinklers. Because the foliage is not wet every time
you water, leaf diseases are minimized.
Drip irrigation is by far the most effective and
efficient way to apply water to garden and landscape
beds or to fruit trees, vines and bushes.
Parts of a Drip System
Drip irrigation systems in commercial orchards, truck
farms and extensive landscape installations can be
rather complex, but in a basic home garden system they
are quite simple.
The basic system for hooking up to a garden faucet has 5
components: a backflow preventer, a pressure regulator,
a filter, delivery tubing and the drip tubing.
Backflow preventers are especially important if you plan
on occasionally fertilizing through your drip irrigation
system. They prevent water from moving from the drip
system back into your water lines should a drop in
pressure occur in the water line.
The pressure regulator reduces the pressure of your
water line down to an appropriate working pressure for
the drip emitters in the drip line, usually about 10 to
25 psi, depending on the type of emitters selected.
Without it the system won’t work properly. The filter
catches sediment such as sand or chunks of lime flowing
through the water lines to prevent them from clogging
the emitters in your drip system.
The delivery tubing carries the water from the faucet to
the garden beds and the drip tubing applies the water
where you want it. There are several types of drip
tubing and emitters. These can be divided into two basic
categories: Tubing into which individual drip emitters
are placed and tubing that comes with emitters already
With the first type you purchase the tubing, typically
1/2-inch poly tubing, and the emitters of your choice.
Then you punch holes in the tubing where you want the
emitters to go and pop one of the barbed end emitters
into each hole. The second type of tubing either has
tiny precut slits from which the water drips or emitters
that are preinstalled inside the tubing.
There are so many different options with each type that
there is not room in this article to delve into all of
them. Instead I’d like to offer my opinion about the two
simplest and best choices for someone starting off
installing their own drip irrigation system for a
vegetable garden or ornamental bed: drip tape and
in-line emitter poly tubing.
Drip tape or T-Tape is an inexpensive, relatively
thin-walled type of tubing with emitters in the tubing.
This type of tubing is great for straight garden beds
but doesn’t curve around corners. I use it in my
vegetable garden beds, placing two drip tape lines down
each bed. It is easy to attach to the 1/2-inch poly
delivery tubing with special barbed connectors that pop
into holes you make in the delivery tubing.
The emitters in the drip tape are a special design where
the water first flows through a zig-zag pathway before
exiting the tubing. This is referred to as a “tortuous
path” or “turbulent-flow” emitter. This design reduces
pressure fluctuations somewhat so that the amount of
water applied stays fairly consistent all the way down
the length of drip line.
In-line emitter poly tubing is constructed of 1/2-inch
poly just like the delivery line. However, it has
special “tortuous path” emitters installed inside the
line as it is made. On the outside all you see is a
small hole where the water drips out. This type of line
can be bent gradually to go around corners, making it my
favorite choice for landscape beds. For tight corners
there are “L” and “T” type fittings as with all other
types of drip irrigation line.
These “tortuous path” emitters are not truly pressure
compensating emitters but do provide some compensation
for variations on pressure. If you have a situation
where drip lines are going to drop several feet in
elevation over the course of the run, there are pressure
compensating emitters that can be purchased and placed
into poly tubing.
With both of these types of drip tubing you can choose
from a range of predetermined emitter spacings.
Depending on the type of line available, spacings
include 6”, 9”, 12”, 18” and 24”. I find that 12”
spacing is best for most home garden and landscape
Building Your System
Building your own basic garden drip system is really
quite simple. In fact, it is rather like playing with
Tinker Toys! Start by doing a little shopping for a good
supplier. While drip irrigation supplies are widely
available, including through some home stores, I suggest
you consider not only price but also the variety of
products offered and whether or not the seller provides
guidance or customer assistance. Local garden centers
and online sources are good choices to consider.
Purchase a backflow preventer that can be attached to an
outdoor faucet. I actually start with “Y” or multi
outlet splitter attachment so I can still attach a
garden hose to the faucet when I need to. The backflow
preventer is attached to one outlet on the splitter.
After the backflow preventer, attach the filter followed
by the pressure regulator. For small home drip systems a
screen type filter works fine.
Next attach the poly tubing used for delivering the
water to the garden area. In my system I purchased a
series of inexpensive valves for use on the poly tubing
so I can control which garden areas are being watered.
The poly tubing can be left on the soil surface and
covered with mulch or buried a few inches below the soil
to get it out of sight, if you like.
At the garden the particular type of drip tubing you
choose takes over to provide the water to the plants.
There are fittings for each connection between various
types of tubing, as well as “L” and “T” fittings, unions
for joining two sections of tubing and end flush
connections that allow you to flush out the lines
periodically. This is where some help from your supplier
can make it easier to know how many of which types of
fittings to purchase. Most fittings are attached to the
tubing by slipping the tubing over a ridged nipple and
then screwing a covering ring down over the outside of
the tubing to hold it tight.
Setting Up Your System
Start by planning out where you want to install drip
tubing and where the nearest faucet is located.
Determine how much delivery tubing you need and how many
feet of drip tubing are required. Buy a little more than
you think you need…trust me.
Emitters generally put out either 1/2 or 1 gallon per
hour, although other rates are available. Depending on
which type you purchase and the distance between
emitters, the flow in a particular line will vary
considerably. As a general rule of thumb, figure on an
outdoor faucet putting out 5 gallons per minute, which
is 300 gallons per hour. Once you put this through the
filter, pressure regulator and into the 1/2-inch line,
you can conservatively figure on about 120 gallons per
hour. This would mean that a line will supply about 120
emitters that drip 1 gallon per hour each or 240
emitters that drip 1/2-gallon per hour.
As a general guide you don’t want to make runs that are
longer than about 250 feet from the source. If you want
to split the line at the source and run it two ways each
could be up to a 250 foot run as long as it doesn’t
supply much over 120 gallons per hour.
Add up the flow rate for all the emitters on series of
lines to ensure that it doesn’t exceed the maximum flow
rate. On my home garden system I have set up several
valves that enable me to run one or two such “zones” at
a time. Keep in mind that all these are general
guidelines and a number of factors will cause variations
Be prepared to experiment a little. There are some handy
additions such as poly tubing valves that can be added
to allow you to turn sections off and on when an entire
length of run proves to be too long, or your water
supply doesn’t provide the rate of flow you thought it
would. Remember, this is like Tinker Toys; so it’s no
problem to take something apart and redesign a section!
While some types of drip line can be buried, I prefer to
keep mine on the surface to minimize clogging and entry
of roots into the emitters. That way I can easily check
to make sure the line is working and fix any problems. I
do however cover the line with mulch in some areas for
personal aesthetic preferences.
I’ve focused on a couple of simple types of drip tubing
in this article. There are many more options well worth
considering. Orchards can be irrigated with drip but can
also be watered very efficiently with microsprayers or
microsprinklers which spit out droplets in a large
circular area down low to the ground to minimize
evaporative losses. There are automatic valves and
timers that can be added to make a system easier to use,
even when you are on vacation!
If you have a fairly large property or special
circumstances such as a significant slope across the
property, it is probably best to hire an irrigation
professional to design a system for you. But for most
gardeners a simple do-it-yourself system is an
easy-to-build weekend project well worth your time and
This year give drip irrigation a try. Start small,
perhaps with your vegetable garden or a set of color
beds in the landscape. You’ll save on water for years to
come while saving time dragging hoses and sprinklers.
Best of all, your garden and landscape plants will look
and perform their best!
Efficient Use of Water in the Garden and Landscape: