How to Install a Garden Irrigation System

Install Your Garden Irrigation System

Most home garden irrigation systems are terribly inefficient and waste untold gallons of water, they produce run-off and wash needed minerals from the soil. The typical spray system puts water on driveways, walks, has double or triple coverage areas, and they dump so much water in such a short period of time that run-off is inevitable.

The best of the garden irrigation systems is the drip system. Drip irrigation systems put metered amounts of water where you want it. Because the water is applied slowly, it penetrates the soil instead of running off as is common in lawn sprays.

A properly designed drip irrigation system will save you up to 80% of the water you currently us in your garden and will improve the quality of the garden in the process.

Common spray system lose water to the wind, and the splashing water also promotes and spreads common garden diseases. Water, sprayed repeatedly on the base of plants or trunk of a tree, will actually damage the bark and allow pests and diseases an easy path into the plant’s tissue. Healthy, properly watered plants are not as attractive to insects as those under stress.

Using less water also means that you do not leach all the nutrients from the soil, and your will need to apply less fertilizer. Depending on where you live in the country, you may be able to grow legumes (peas, beans, clover) as cover or winter ‘green manure’ crops, and these will provide the nitrogen your soil needs.

In the drier parts of California, there are plenty of minerals, and nitrogen is the only nutrient that needs to be replaced. Since nitrogen is so soluble, it will leach out of the root zone very easily – drip irrigation keeps it where you need it.

So, if you would like to save money and 80% of your water, eliminate chemicals and pesticides, help the environment and have healthy plants, let’s continue…

Drip Irrigation Basics

1) Drip irrigation systems operate at low pressure and low volume.

Since most homes have water pressures from 45 PSI to 60 PSI (ours is ~90 PSI), you will need a 10 to 20 PSI pressure regulator to keep from blowing the system apart. The in-line regulators run me about $3.85 – $5.00. The regulators I use have IPS threads so they can screw into your piping and may be added either below a spigot, or they may be screwed direct to a spigot’s threaded nozzle.

2) All water contains some contaminates.

These can be sand or grit, scale from pipes, rust particles, etc. Most emitters have extremely fine orifaces and clog easily. You should use a filter to clean the particulates from the water to prevent clogging the emitters.

3) Tubing

Tubing is used in drip systems instead of pipe. This allows you to posistion the delivery system where it is needed. The soft, flexible tubing comes in several sizes; I use 5/8″. Make sure all the fittings are sized to match (usually not a problem since most places only carry one size). I buy mine in 500′ rolls for about $0.10 / foot

4) Fittings:

Drip systems are easy to install and require only a sharp knife or clipper to work with the tubing. Connections are slip-fit and no specail tools or wrenches are needed.

Almost all fittings cost less than a buck each, and there are only a few that you will need. Let’s look at the important ones.

You will need an IPS to Slip adapter to transition from the threaded delivery sytem to the tubing. This adapter screws onto the filter or regulator threads and the tubing gets pushed into (or over) the other end.

‘Tee’s, Slip-connectors, and perhaps ‘El’s are all that is usually required. Depending on how you deliver the water, barbed connectors (with or without a regulated emitter) and speghetti tubing may be required (pennies apiece and per foot).

There are other handy fittings you can get and may find useful, such as quick-connect fittings with a shut-off ball valve built into them for swapping delivery lines around, end-caps with a screw-on cap that allows you to quickly flush a line (not essential, and ring made out of 3/4″ or 1″ PVC pipe can slip over the tubing to provide a reasonable termination).

5) Emitters

An emitter is any device that meters water from inside the tubing to the garden; these can be individual drip emitters, drip tapes or tubing with molded in emitters, soaker hoses or a variety of mini-spray heads.

Here is where it gets fun. There are hundreds of different emitters, from spinning ‘micro sprinklers’ full and part-circle sprays heads, drippers, and drip-tape. You can mix and match any of these, but tmixing parts makes balancing the system very difficult.

I prefer to standardize one one type to make balancing water delivery easier. Standardization also means repairs are easier to perform since all your spares fit.

Drip and spray emitters come in everything from fractions of a gallon to multiple gallons per hour flow rates (1/2 gallon per hour, 1 gallon per hour, etc.). Sprays can be confusing since, besides the different flow rate, they also have different areas they cover. Since sprays can  spread disease, I now use drip tapes or 1/2, 1 and 2 gph drippers for almost all my garden and orchard needs.

Drippers deliver water to one spot; you can use multiples to deliver water around the root zone. They do tend to form a densely wet area where they sit. I use these under trees and covered with mulch, to irrigate outlying orchards trees

Sprays – lots of choices here. Micro-sprays may be rotating or fan types, supplied as a simple plug-in item or they may come with a mounting stake attached. You should be aware that sprays, while a great way to spread water over a large are but have the issues of leaving the plants wet  which is conductive to disease formation and may spread fungal diseases from one plant to another. Also, evaporation in the air means 50% may not hit the ground during normal days, and on windy when you really need the water,  90% of it is lost.

Soaker hoses, preformed drip tubing, and drip-tape:

This is where I am taking all my gardens at the moment. The tapes or tubing comes with emitters molded in (every 8″ to 1′ apart), in various delivery rates.When used under a layer of mulch, these provide an even level of moisture. The drip-tape comes in two types: tubing (just like your delivery line, durable but $350 per 1,000′) or tape (costs me about $50 for 1,600 foot rolls).

The flat-rolled ‘Row Drip’ tape is cheapest, requires 10 PSI maximum pressure, and requires special fittings (about $1 to $1.50 each). The fittings plug onto the supply lines, and the tubing slides over a barb and a collar screws over the tape, holding it in position. The tape is not the most permanent way to go, but works well for a year or two.

Here is a picture of a drip tape system going in. The excess moisture is from flushing the lines before hooking up the drip tape.

The delivery system is standard low-pressure 5/8″ drip line with slip-on fittings. A pressure regulator at the spigot keeps the water at 10 PSI.

The drip tape adapter slips onto the drip line, and the tape is secure over a barb and twist-to-lock collar. The tape is available in several weights, emitter spacings and delivery amounts.

Irrigation system details
Irrigation system in a row Here is the tape pressured up, laid in place, and being covereed with mulch. The mulch cap protects the tape and keeps water from evaporating.This row will get 10 to 12 minutes of water every other day, will have even moisture levels, and there will be very few weeds to contend with. Water distribution is very uniform at the root depth, and 750 ‘ of rows are watered from a single hose bib.

The heavy mulch layer in the pathways further reduces weeds.

Here is a similar row with covered drip tapes and mulched pathways. The chard is happy, water requirements are low, and there are few weeds to contend with. An irrigated garden bed
One of the problems with the low cost drip tape is that the emitters are not pressure regulated, and they run at very low pressures.

This means that if you have a hillside garden, like I do (see the photos above), more than one pressure regulated zone may be required. I have created 4 separate zones from one single valve, and and moisture uniformity is much better.

Here is a photo of one of the regulators. This one is about $7, and has standard screw in fittings. Even simpler ones start at less than $4. Tubing adapters are available in both male and female ends to make connection a snap. The entire system is regulated to 20 psi to keep from blowing the slip fittings apart, and each zone is regulated down to 10 psi, the maximum rated pressure for the tubing.