Drip Irrigation Design Guide-Design FAQs

Drip Irrigation Design Guide-Design FAQs

Designing & Planning Your System

   Content Covered in this Section:   

   Planning Your Layout

   Grouping Plant Types

   Determining Your Water Source Flow Rate & Pressure

   Water Connection Options

   Calculating Total Flow & Creating Watering Zones

   Watering Schedules

   Design FAQs



Design FAQs

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 out 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 50 to 70 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 elevation 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 emitter or sprayer. 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

• Delivers the stated gph (gallon per hour) even if pressure 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.

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