Planning Your Layout

Before you begin to design your drip irrigation system, it’s best to start by making a sketch of the areas that you want to water. Be sure to include and label all your plant types, including shrubs, trees, ground cover, flower beds, vegetable gardens and containers.  Identify all the site watering sources, what type they are, and any existing connections. Add any buildings, walkways, retaining walls or obstacles that you may need to work around.

Draw out each run of drip mainline tubing and any laterals that will be needed to supply water to each planting area. For plants that are away from the mainline, draw out runs of 1/4” micro tubing to cover each plant. Working from a good plan will help aid you when making a materials lists and is essential in designing an efficient drip irrigation system.

 

Grouping Plant Types

Plants of similar sizes and growth habits generally have watering requirements that are much the same. When designing your drip irrigation system always try to group watering zones by plant moisture needs and local climate conditions (shade, partial shade, full sun).

 

Consider the following:

• Plants that need frequent, shallow watering, like annual flowers and ground cover should be grouped separately from those needing less frequent, deep watering, like trees.

 

• Seasonal plantings like crops or vegetable gardens should be kept separate from permanent plantings like shrubs. Install inexpensive flow control valves to shut off these areas when not in use.

 

• Create separate zones for plants in the shade versus hot, sunny spots.

 

• Container plants should be watered separately from plants in the ground. They have confined root systems and may dry out more quickly.

 

QUICK TIP: 

 

 

Drip Components Options by Plant Types

Containers or Flower Pots: Use pressure compensating drip emitters in small containers with 1/4" micro tubing or attached to 1/2" solid tubing. Use 1/4" soaker hose dripline, stream bubblers or sprayers in larger pots.

Trees and Shrubs: Use either pressure compensating or non pressure compensating drip emitters with 1/2" drip tubing or off 1/4” micro tubing attached to 1/2” drip line. Use soaker hose dripline to create drip rings around medium and large shrubs and small to large trees.

 

 

 

 

 

Flower Beds & Ground Cover: To cover small flower beds and ground cover, use 1/4" soaker hose dripline. For larger beds and ground covers, use micro sprayers and jets.

 

 

Vegetable Gardens & Berry Bushes: For small vegetable gardens and berry bushes, use 1/4" soaker hose dripline with 6” or 12” drip emitter spacing. For large vegetable gardens and berry bushes, use 1/2” soaker hose dripline with 12” to 36” emitter spacing. For gardens with uneven plant spacing, use 1/4” micro tubing with inline drip emitters or 1/2” solid drip tubing with self installed drip emitters.

 

 

Vineyards: Use 1/2” or 3/4” solid drip tubing attached to trellis. Install pressure compensating drip emitters in tubing facing down.

 

 

 

Slopes: When designing a drip system for slopes, it’s best to install drip tubing along the parallel of the slope and install .5 gph drip emitters. Lower flow emitters along with shorter but more frequent watering times will help prevent runoff and soil erosion.

 

 

 

 

 

 

Determining Your Water Source Flow Rate & Pressure

The flow rate of your water supply determines how much water you have available for your drip emitters and micro sprinklers. It is commonly measured in gallons per hour (GPH) or gallons per minute (GPM). The greater the rate of flow of water, the more drip emitters you can install on a single watering zone and the more zones you can run from a single irrigation valve.

 

Water pressure is the force pushing the flow of water through your system and is measured in pound per square inch (psi). If your water pressure is too low, drip emitters and sprayers won’t work properly. Too high a pressure and drip tubing and fittings can blow apart. A standard drip systems optimal operating pressure is between 20 to 30 psi. The higher the pressure, the greater the need for a pressure regulator in your drip system.

 

To determine the flow rate out of your faucet, follow these five steps:

1.    Turn off any running water sources in the house (Washer, Dishwasher, Shower….ect)

2.    Place a 5-gallon bucket under the faucet.

3.    Quickly turn on the faucet so that it is fully open. 

4.    Record how many seconds it takes to fill the 5-gallon bucket (gallons per second).

5.    Calculate your flow rate to determine Gallons per Hour:

 

(5 gallons ÷ X seconds) X 60 seconds/minute X 60 minutes/hour = Gallons per Hour (GPH)

 

Example: If it takes 75 seconds to fill our 5-gallon bucket. The formula is:

(5 gallons ÷ 75 seconds) X 60 seconds/minute X 60 minutes/hour = 240 GPH

Now you know the limit of emitter output for your system. In the example above, you can place a total of 240 1-gph or 480 1/2-gph drip emitters on your system. Note: This is only one factor in designing your system. You also need to consider water pressure and maximum run for mainline tubing.

 

QUICK TIP: The maximum recommended flow rate for 1/2" drip poly tubing is 240 GPH (4 GPM).

Although your water source may flow more the 240 GPH, it’s important to understand that the size of the drip tubing will limit how much water can pass through.

 

QUICK TIP: The maximum recommended flow rate for 3/4" drip poly tubing is 540 GPH (9 GPM).

To determine the water pressure at your faucet, follow these four steps:

1.    Purchase an inexpensive water pressure gauge at your local hardware store (Around $10).

2.    Screw the pressure gauge onto your hose bibb.

3.    Turn on the hose bibb and read the psi (pounds per square inch) off of the gauge.

4.    Test the pressure at each water source you will connect too.

 

Drip systems operate best between 20-30 psi. Most household water systems operate at 50-70 psi. Install a pressure regulator to reduce the pressure if you measure above 40 psi.

 

QUICK TIP: If your household water pressure is at 90 psi or greater, it may compromise the operation of your drip regulator.

If this is the case, we recommend hiring a plumber to reduce the pressure of your household water system.

 

 

Water Connection Options

In general, most of the water source connections in drip irrigation fall into two main categories; Hose Bibb and Irrigation Valves. While irrigation valves are more specific, hose bibbs tend to cover a much wider range of connections.

 

Known as a spigot, faucet or hydrant, hose bibbs offer the most convenient water source connection available for your drip system. Standard hose bibb connections come with 3/4” male hose threads and use hose washers to make water tight seals. If your water source connection has pipe threads, Irrigation Direct sells adapter fittings to convert either 1/2” or 3/4" male and female pipe threads to 3/4" male hose threads.

 

 

For larger drip systems with multiple zones, irrigation valves and controllers are typical installed. This usually involves more work in setting up and installing. Valves typically use pipe threads for connections and require Teflon tape to make water tight seals. It also may require you to cut into your existing household water main to supply the valves. If you are unsure about how or where to install irrigation valves, it may be best to contract an irrigation professional to help with installation.

 

 

 

 

Determining Your Water Source Flow Rate & Pressure

The flow rate of your water supply determines how much water you have available for your drip emitters and micro sprinklers. It is commonly measured in gallons per hour (GPH) or gallons per minute (GPM). The greater the rate of flow of water, the more drip emitters you can install on a single watering zone and the more zones you can run from a single irrigation valve.

 

Water pressure is the force pushing the flow of water through your system and is measured in pound per square inch (psi). If your water pressure is too low, drip emitters and sprayers won’t work properly. Too high a pressure and drip tubing and fittings can blow apart. A standard drip systems optimal operating pressure is between 20 to 30 psi. The higher the pressure, the greater the need for a pressure regulator in your drip system.

 

To determine the flow rate out of your faucet, follow these five steps:

1.    Turn off any running water sources in the house (Washer, Dishwasher, Shower….ect)

2.    Place a 5-gallon bucket under the faucet.

3.    Quickly turn on the faucet so that it is fully open. 

4.    Record how many seconds it takes to fill the 5-gallon bucket (gallons per second).

5.    Calculate your flow rate to determine Gallons per Hour:

 

(5 gallons ÷ X seconds) X 60 seconds/minute X 60 minutes/hour = Gallons per Hour (GPH)

 

Example: If it takes 75 seconds to fill our 5-gallon bucket. The formula is:

(5 gallons ÷ 75 seconds) X 60 seconds/minute X 60 minutes/hour = 240 GPH

Now you know the limit of emitter output for your system. In the example above, you can place a total of 240 1-gph or 480 1/2-gph drip emitters on your system. Note: This is only one factor in designing your system. You also need to consider water pressure and maximum run for mainline tubing.

 

QUICK TIP: The maximum recommended flow rate for 1/2" drip poly tubing is 240 GPH (4 GPM).

Although your water source may flow more the 240 GPH, it’s important to understand that the size of the drip tubing will limit how much water can pass through.

 

QUICK TIP: The maximum recommended flow rate for 3/4" drip poly tubing is 540 GPH (9 GPM).

To determine the water pressure at your faucet, follow these four steps:

1.    Purchase an inexpensive water pressure gauge at your local hardware store (Around $10).

2.    Screw the pressure gauge onto your hose bibb.

3.    Turn on the hose bibb and read the psi (pounds per square inch) off of the gauge.

4.    Test the pressure at each water source you will connect too.

 

Drip systems operate best between 20-30 psi. Most household water systems operate at 50-70 psi. Install a pressure regulator to reduce the pressure if you measure above 40 psi.

 

QUICK TIP: If your household water pressure is at 90 psi or greater, it may compromise the operation of your drip regulator.

If this is the case, we recommend hiring a plumber to reduce the pressure of your household water system.

 

 

Watering Schedules

When determining your water schedule, it’s important to understand that there several factors that need to be taken into account. Plants with deep root zones require longer watering then those with shallow root zones. Conditions such as temperature, wind, humidity, sun exposure and soil type will all have an effect on how much water can be applied on one time.

 

The follow watering times and intervals are meant to be guidelines to help you with setting up a watering schedule. When starting, it’s best to water for 2 or 3 irrigation cycles. Check for moisture around drip emitters and root zones. Be sure the soil is neither too wet nor too dry and the plants look healthy. Make gradual changes to your schedule to adjust for your drip systems conditions. As the seasons change, increase or decrease your watering schedule accordingly.

 

Drip Emitters & Soaker Hose Dripline:

 

Example: In late spring time, a row of small trees would need to be watered for 1 to 2 hours with a scheduled interval of every 2nd or 3rd day.

Micro Sprays and Jets:

 

Example: In the middle of summer, a flower bed & ground cover would need to be watered for 30 to 60 minutes with a scheduled interval of every day or 2nd day.

 

 

Design FAQ’s

Q. Where do I start? The best advice when planning a drip system is to start small. Designing and installing a small drip system will give you valuable experience if and when you decide to expand. Start with containers, pots or a small garden. Irrigation Direct offers several drip irrigation starter kits to help you get started.

 

Q. What is my water source’s flow rate? Flow rates will vary from location to location. Saying that you have enough flow might work for a small drip system, but may cause problems when designing a large system. Follow the instructions in the design section to determine your water sources flow rate.

 

Q. Do I need to install a filter? Designed to filter our rust, sand or debris, installing a drip filter is necessary to protect your emitters from clogging over time. Even if your drip system is connected to your household water source, installing a filter is a low cost solution to protect your investment.

 

Q. Do I need a pressure regulator? Most household pressure is around 40 to 60 psi. Drip irrigation systems operate in the 20 to 30 psi. Excessive pressure can cause fittings and emitters to blow off the tubing. Follow the instructions in the design section to determine your water sources pressure.

 

Q. Which pressure regulator do I need? Most drip systems will work with a 20 psi regulator. Large drip systems with elevations changes or systems with hanging baskets do better with a 30 psi regulator.

 

Q. How far can I run my 1/2” drip tubing? This is the main feeder line for your drip irrigation system. It is used to create manifolds and branch lines. The maximum distance that you can run drip tubing will vary with the number of emitters you install and the spacing between emitters, but here are two conservative guidelines:

 

Maximum Run per circuit (Zone): 200 ft

 

Maximum Flow Capacity: 240 gph

 

Our Drip Tubing Maximum Run Chart will help you compare different scenarios. The maximum run will increase if you use low-output emitters (1/2 gallon-per-hour). Increasing pressure regulator size from a 20 psi regulator to a 30 psi regulator will also extend the distance that you can run drip mainline.

 

 

 

Q. How many drip emitters can I install? You can add as many drip emitters as your flow rate will support. A typical hose bibb delivers 240 gallons per hour. So you have 240 gallons available for your emitters to “consume”. Simply add up the total number of gallons to be consumed by the emitters that you plan to add. You can put 240 1 gallon-per-hour emitters on the line (or 480 1/2 gallon-per-hour emitters or 120 2 gallon-per-hour emitters).

 

Keep in mind that if you’re adding adjustable emitters and micro sprays, the output can be in excess of 30 gallons per hour for each output. It doesn’t take many sprays to use up those 240 gallons. 

 

Q. How far can I run my 1/4” micro tubing? Due to its smaller size, any single run of micro tubing must not exceed to 50 feet.

 

Q. Can I bury my drip tubing? It is not recommended to bury drip tubing. Drip tubing can become compressed over time causing reduced water flow to your system. If you need to bury your drip tubing, it’s best to sleeve it in solid PVC pipe.

 

Q. Can I expand my system? Expanding your drip system will depend on the reserve of water left over from your initial installation. Make sure you know your water source flow rate and the total flow that your current drip system is using. This will allow you to determine any excess water that may be used to expand your system.

 

Q. How long do I water my drip system? Watering times will vary from location to location and also on the current season. Reference the charts in the watering schedule section to determine your watering time needs.

 

Q. What’s the difference between PC and non PC emitters? Pressure compensating emitters are the best choice for many applications. If your landscape has elevation changes (hills, dips, etc.) go with pressure-compensating emitters. They have a diaphragm inside which maintains the same water flow through the emitter even if the elevation (and pressure) changes.

 

With non-pressure-compensating emitters, the emitters on the higher elevations will distribute less water than those at the bottom of the slope. Non-pressure compensating emitters are a great choice for flat landscapes and with gravity-fed drip systems.

 

Pressure Compensating Emitters

• Deliver the stated gph (gallon per hour) even if pressures range is from 10-50 psi
• Works well with elevation changes
• Self-flushing to reduce clogging

 

Non-Pressure Compensating Emitters

• The output will vary with changes in pressure and elevation
• Less expensive than pressure compensating emitters
• Recommended pressure: 15-20 psi

 

Q. Can I retrofit my existing sprinkler system to drip? Retrofitting an existing sprinkler system can be done by adding adapter fittings to convert the sprinkler risers to accept a water source connection assembly or multi port drip emitters. Follow the instructions in the design section for information on retrofitting.

 

Q. Can I combine both sprinklers and drip in the same system? We do not recommend mixing sprinklers and drip irrigation on the same system. The problem lies in the output difference between the two. Sprinklers are designed to deliver a lot of water over a very short time while drip emitters and components are designed to deliver lower amounts of water over a very long time. Running both types on one system would cause over watering in one case and under watering in another.