Complete Guide to Drip Irrigation

Smart water management is the only way to healthy, happy plants and trees. Among the many methods and tools available to manage water wisely, drip irrigation remains one of the most popular and effective. Also referred to as low‐volume or micro irrigation, drip systems are ideal for virtually all landscaping applications!

Drip irrigation can use either PVC pipe or polyethylene tubing (or a combination of both). PVC systems are usually reserved for larger‐scale applications (like farming), while polyethylene tubing is the choice for home gardening. We'll be covering polyethylene in this guide, but the basic concepts remain the same.

Components of a Drip System

There are three primary components to any drip system: tubing, fittings to connect tubing, and the emitters that deliver water.

Tubing

Plastic tubing is the backbone of any drip system. All of our tubing is manufactured from top‐quality, UV‐resistant Union Carbide #7510 polyethylene and/or Dow DFDA‐7510 virgin LLDPE (Linear Low Density Polyethylene) resin. This is contractor‐grade tubing, designed to help eliminate pipe failures due to UV light damage and environmental stress cracking.

• In a typical home garden setup, 1/2" tubing is used as the main line that supplies 1/4" tubing, to which emitters are connected. But 3/4" (and larger) tubing can be used for larger systems.
• So‐called 1/2" tubing actually varies in size — from 0.455" OD to 0.900 OD! The large tubing we offer measures 0.700" OD (0.600" ID), the size most commonly used by professional installers.
• 1/4" tubing is much more uniform in size across brands, typically measuring an exact 1/4" OD with a 0.170" ID. 0.155" and 0.160" ID tubing is out there, however.
• Worried about kinks, cracking or deterioration? If you require a sharp bend in your line, cut the tubing and use an elbow fitting.
• Already have 1/2" tubing (with an OD from 0.455" 0.710") that you want to incorporate into a system using our 0.700" OD tubing? Adapters are available!

Fittings

Tubing and emitters alone will deliver water, but without fittings a drip system is little more than a leaky hose. Fittings allow for an irrigation system of greater complexity and efficiency.

• Fittings that connect to 1/2" tubing use a compression fit. Tubing goes inside the fitting and is held in place by a sharp edge angled toward the inside of the fitting. These fittings will hold tubing with pressure up to 50 psi, but pressures above 25 psi should be avoided in any drip system.
• Threaded connections are available, allowing you to connect to things like PVC pipe and hose bibbs. We also offer adapters that glue into unthreaded PVC, allowing for a standard drip compression connection.
• 1/4" fittings typically use barbed ends that are inserted directly into the end of 1/4" tubing, or into holes made in 1/2" tubing. Our 1/4" fittings will work with any tubing that has an ID of 0.155" to 0.170".

Emitters

Although "drip" is how we usually refer to low‐volume/micro irrigation, there are actually several emitter types. Serious gardeners will use different emitters depending on a plant's needs, the soil type, or the landscape design.

Pro Tip: For garden features/locations with a 5 foot elevation difference (from the main supply line of the drip system), pressure‐compensating (PC) emitters are recommended. Their internal design will guard against any variations in flow caused by the change in pressure.

• Drip Emitters — The most precise option, delivering water directly to the soil at the root zone at very slow rates. Drip emitters are suited to most vegetable gardens, trees, hanging baskets etc. Because of the low discharge rate, the watering cycle is usually longer.
• Micro‐Sprays — The suggested emitter when low volume, overhead irrigation is desired. Ground covers, ice plants, etc. are often irrigated with micro‐spray emitters. Plants that prefer some humidity (like ferns) will benefit from this method as well.
• Bubblers — Most often used for shrubs and trees. With their higher discharge rates, they have short watering cycles. Because bubblers can operate at high pressures they are particularly useful for conversion from conventional sprinkler to low volume systems.
• Dial‐A‐Flo™ Emitters — Can be adjusted from a drip emitter to a stream bubbler as the discharge increases. The unit is calibrated so that the desired discharge can be selected by rotating the cap. These versatile emitters can also be used in an inverted (upside‐down) position — an ideal solution for hanging baskets. Dial‐A‐Flos are easily taken apart for cleaning.
• Maxi‐Flo Bubblers — Are adjustable, six‐outlet PC emitters. Simply connect 1/4" tubing to an outlet, adjust to the ideal flow rate (0–20 gph) and let nature go to work! These bubblers are designed to be used with 1/2" PVC and feature a 1/2" fips inlet.
• Laser‐Drilled Emitter Tubing — Perfect for watering closely spaced plants, new ground cover, hedges and trees, this is a line of 1/4" tubing that comes with holes every 9 inches for water to seep out of at a steady pace. At 20 psi, expect approximately 2.3 gph per foot.
• It's generally recommended that different emitter types be put on separate circuits and operated independently, either manually or through a multi‐zone timer.
• Because watering times are typically very long, timers are an especially good idea for drip systems: after several hours, it's easy to get distracted and forget to turn the system off!
• In addition to emitters and tubing, you'll need a vacuum breaker installed to keep contaminated water from being siphoned into your home's water supply. You'll also want to include a filter to prevent clogging from sediment and other particles. And unless you have very low water pressure, a pressure regulator is often another necessary addition: drip systems perform best with a 20–25 psi supply pressure.
• If you're converting an existing sprinkler system into a drip irrigation system, we offer riser fittings that will cover the 1/2" pipe usually holding sprinkler heads. You'll remove the heads and attach the riser fittings to run your drip tubing from there instead.

Design Tips

Before you start anything, you need to determine the water needs of the plants and trees you're looking to address. This is necessary to ensure you're choosing the best type of emitter for each plant or zone, especially when it comes to vegetable gardens.

• Map out your system, making sure to include measurements, emitter locations and flow rates, and other information you'll need during installation (or even purchasing). Pay extra close attention to tubing and emitter sizes!
• Mind your flow rates: in addition to knowing how much water a plant needs, you need to consider the type of soil it's found in. Too fast a flow in the wrong soil can lead to runoff and waste, while a slow flow in quick‐draining soils may not provide enough water.
• Sandy, coarse soil will drain more quickly. A 1 gph emitter will wet an area about 11–15" in diameter on the soil surface, which tapers down as the water moves further into the soil.
• Loamy soil is a gardener's dream, striking the perfect balance between coarse and dense. 1 gph emitters will wet the surface about 15–18" in diameter.
• Dense clay soil will drain slowly, with a 1 gph emitter wetting a diameter of 20–24" on the soil surface.
• Tubing has limits! Keep in mind that each run of tubing needs to be kept under a certain length — and below a certain flow rate — or else you're likely to experience problems with pressure loss and uneven watering.
• When it comes to 1/2" tubing, there's something called the 200/200 rule: keep each individual run of 1/2" tubing under 200 feet from the water source, and make sure that the combined flow rates of all of the emitters on that run don't exceed 200 gph. For 3/4" tubing, follow the 480/480 rule.
• For 1/4" tubing, the shorter the run, the better. Although there is a 30/30 rule (30 foot max length, 30 gph max flow rate), others recommend keeping runs of 1/4" tubing under 20 feet. Keeping these runs short should be fairly easy, since 1/4" tubing typically comes off the main 1/2" line only far enough to reach nearby plants or trees.
• You may be able to get away with longer runs of either size provided the number and/or flow rates of the emitters on it are below the 200 gph (for 1/2") or 30 gph (for 1/4") maximums. For example, a 275 foot run of 1/2" tubing with emitters that add up to 75 gph should perform fine.
• As a general rule, keep the combined length of your main and lateral lines (1/2" and 1/4") under 400 feet from the water supply. If this doesn't cover your whole garden or yard, consider installing multiple zones by either splitting the supply from the outdoor faucet (provided you have a 40+ psi supply), installing at multiple faucets, or using a multi‐zone timer.
• Multiple irrigation zones allow you to water a greater area without the risk of pressure loss or other problems. Zoning can be accomplished in several ways depending on the situation and your garden's needs.
• As mentioned above, the simplest way to create multiple zones is by splitting the output from an outdoor faucet using a wye fitting (commonly referred to as a "garden hose splitter"). Most municipal water supplies have a pressure of 40 psi or above, so you shouldn't encounter any problems supplying two zones at 20 psi each (don't forget pressure regulators at each hose connection if you'll be running them simultaneously; a single regulator at the inlet will suffice for zones run one at a time).
• Another simple method is to use in‐line valves to create a manually‐controlled zoning system. A valve is installed before each zone, allowing you to manually control which area gets water. You'll need a good memory and a lot of dedication for this method to work, but it does accomplish the task.
• Multi‐zone manifolds and timers are the most advanced — and powerful — option. These devices utilize solenoid valves — electronically controlled valves that open/close themselves — to automatically control which valves are open at a given time. Simply program the unit, connect it to the supply and your drip system hoses, and let nature take care of the rest!
• One creative alternative to these traditional zoning method is to use quick connect fittings to manually connect and disconnect a given drip line. Multiple hoses feeding different zones can be switched out at the same outdoor faucet within seconds and without tightening. Just don't forget where you're watering!

Installation Tips

Installation itself is usually a pretty straightforward affair: tubing is laid out next to the plants, a hole‐punch is used to pierce it, and an emitter is placed in the hole.

• In most applications, 1/2" tubing is used to supply individual 1/4" feeder lines — but many will stick emitters directly into 1/2" tubing. Stakes are used to keep the tubing in place and close to the ground.
• A typical drip system for a home garden will have the following layout at the water source (usually an outdoor faucet hose bibb, sometimes a PVC supply pipe) — this is often referred to as the "faucet assembly":
• A pressure regulator connected to the faucet hose bibb or supply pipe, followed by a filter (straight in‐line filters can be directly connected to the regulator; wye style filters will need a female hose adapter).
• A vacuum breaker is then connected to the filter, followed by a compression adapter, which will allow you to go from the male threads of the vacuum breaker outlet to a compression end which accepts 1/2" drip tubing.
• Most tubing can be buried, but doing so runs the risk of clogging or collapsing the line; look for UV‐resistant tubing that will not break down when exposed, and cover only with mulch.
• Afraid of putting an emitter in the wrong spot? Thanks to goof plugs, you don't need to be! Beyond remedying hole‐punch mistakes, goof plugs allow you to utilize old tubing in good condition for new layouts. Simply replace unnecessary emitters with goof plugs, and make new holes.
• Another plug that comes in handy is a bug plug, which is installed at the end of a line. This allows water to still flow through, but prevents bugs from getting in and clogging or damaging the line.
• Pro Tip: For new installations, we recommend leaving the end of the tubing uncapped and flushing the system before installing emitters and caps. This will help you find any leaks, and flush out any sediment.
• If you live in an area with freezing winters, your drip irrigation system will need to be "winterized" — something you're probably (hopefully!) used to.
1. Disconnect the faucet assembly (regulator, filter, vacuum breaker, compression adapter) and store it indoors. Remove batteries from timers.
2. Open any valves in the system and remove end caps to drain any water remaining in the tubing — when possible, lift the line slightly to facilitate draining. Once drained, close/cap off both ends of the line.
3. Buried lines should be fine, but if your tubing is above‐ground you may want to roll it up and bring it indoors to avoid freezing damage.

More facts, tricks, and tips

As with any plumbing installation, there will always other factors that should be considered. For instances, the optimal duration and frequency for watering with a drip irrigation system vary widely depending the specific circumstances, including the type of soil, climate, plant species, and stage of plant growth. Here's a general guideline to help you get started, but remember, monitoring your soil and plants is key to fine-tuning your watering schedule:

Soil Type

• Sandy soil: Requires more frequent watering because it drains quickly. Shorter, more frequent watering sessions are best.
• Clay soil: Retains water longer, so it needs less frequent watering. However, when you do water, it should be done slowly and for a longer period to ensure deep water penetration without runoff.
• Loamy soil: Has good water retention and drainage balance. Watering can be less frequent than sandy soil but more so than clay.

Climate

• Hot, dry climates: May require daily watering, especially for vegetables and plants with high water needs.
• Cool, humid climates: May require less frequent watering. It's essential to adjust based on rainfall to avoid overwatering.

Plant Type and Growth Stage

• Vegetables and annuals: Often have higher water needs, especially during peak growth and fruiting stages.
• Established trees and shrubs: Generally require less frequent watering but with longer duration to encourage deep root growth.
• New plantings: Need more frequent watering to establish roots, often daily or every other day for the first few weeks, then gradually reducing frequency.

General Guidelines

• Frequency: Start with watering 2-3 times a week for most plants and adjust based on the factors above. Some plants may need daily watering in extreme heat, while others may thrive on once a week.
• Duration: Begin with watering for about 30 minutes to an hour per session and adjust based on observation. The goal is to moisten the soil to the depth of the root zone (6-12 inches for most vegetables and flowers, deeper for trees and shrubs).

Monitoring and Adjusting

• Soil moisture: Check soil moisture at about 6 inches deep. If it's dry, increase watering frequency or duration. If it's soggy, decrease watering.
• Plant health: Look for signs of over or under-watering in plants. Wilted, yellowing, or dropping leaves can indicate watering issues.

Other factors to consider

Is drip irrigation the solution for you? It's something that should be carefully considered. Here are some more thoughts to keep in mind:

• Initial Cost and Set‐up Complexity: The initial investment for a drip irrigation system can be higher than traditional watering methods, particularly for large areas or complex landscapes. The system requires careful planning and installation to ensure that all plants receive adequate water.
• Maintenance Requirements: Drip irrigation systems can be prone to clogging and may require regular maintenance to keep the emitters or driplines clear. This is especially true in areas with hard water or when using water from ponds or streams, which may contain sediment or algae.
• Damage Risk: The tubing and emitters can be damaged by garden tools, or UV exposure from the sun's rays. Repairing damaged parts can add to the maintenance cost and effort.
• Overwatering Potential: Without proper management, there's a risk of overwatering plants. Because the water is delivered directly to the roots, it's not always easy to observe when the soil has received enough moisture, potentially leading to root rot or other water‐related issues.
• Limited to Certain Landscapes: Drip irrigation is ideal for row crops, vegetable gardens, and densely planted areas. However, it might not e as effective or practical for watering large areas of turf or gardens with widely spaced plants without significant modification or supplemental watering methods.
• Learning Curve: For those new to drip irrigation, there can be a learning curve in understanding how to set up and adjust the system correctly for different plants and changing seasonal water needs.

As we all seek out smarter ways to use water and deal with shortages, don't fret: your garden doesn't need to be among the things compromised or sacrificed. By using less water more wisely with a drip irrigation system, you can make both plants and people happy!

Ready to set up your new drip system? We've got everything you need!