Guide to Drip Irrigation Systems

Drip irrigation, also known as micro-irrigation or trickle irrigation, is an efficient irrigation method that saves water and nutrients by allowing water to drip slowly into the roots of plants, either onto the soil surface or directly onto the root zone. Drip irrigation systems distribute water through a network of valves, pipes, tubing and emitters. Compared to other types of irrigation that distribute water unevenly, drip irrigation helps avoid runoff, evaporation, and overwatering. With proper installation and maintenance, drip irrigation can significantly reduce water use while maximizing crop yields. This guide provides a comprehensive overview of drip irrigation systems, their components, design considerations, installation and maintenance.

How Drip Irrigation Works

Drip irrigation works by applying water slowly and directly to the roots of plants. Small amounts of water are emitted over time through emitters and drippers that are placed along tubing or tape installed above or below the soil near the base of the plants. The water seeps into the soil and is absorbed by the plant roots. Applying water at a slow and steady rate allows the soil to absorb all the moisture without any runoff or evaporation. This results in optimal plant growth while conserving water.

The tubing and emitters that make up a drip system form a water delivery network that can be configured into different layouts and customized for each garden space. Drip irrigation tubing and emitters come in a variety of types, flow rates and installation methods. The system can be expanded by adding components as needed. Valves, filters, pressure regulators and control devices allow for precise regulation of water flow and automation.

Benefits of Drip Irrigation

Drip irrigation offers numerous advantages over other irrigation methods:

Conserves water – Drippers apply water slowly and directly to the roots which reduces runoff, evaporation and overspray. Less water is wasted compared to sprinklers and hoses.
Helps prevent disease – Leaves and fruit stay dry which reduces mold, fungus and rot that can occur from overhead watering.
Reduces weeds – Water only reaches plant roots rather than germinating weed seeds between rows.
Saves time – Automated systems allow for watering without daily oversight. Drip tubing lasts for years, reducing maintenance.
Uses less fertilizer – Nutrients are applied directly to the roots along with water, reducing waste.
Adapts to any space – Drip tubing is flexible, allowing for customized watering patterns and easy expansion.
Improves plant health – Slow and even watering without wetting the leaves promotes stronger roots and plant growth.

For gardens and farms looking to maximize water efficiency and crop quality, drip irrigation is an excellent choice. The initial investment pays for itself over time with significant ongoing savings on water, fertilizer and maintenance costs.

Drip System Components

A drip irrigation system is made up of several components that work together to distribute and control water flow. The main elements are:

Tubing

Tubing carries water from the water source to the plants. The most common types are:

Drip tape – Flat, thin polyethylene plastic that easily lies along rows. Built-in emitters are evenly spaced throughout the tape. Made for a single growing season.
Micro tubing – Small diameter polyethylene tubing suited for permanent use. Emmiters and drippers attach along the length of the line.

Emitters and drippers

Emitters (also called drippers) are small devices inserted into irrigation tubing that release water at very slow rates of 1 to 2 gallons per hour. Types include:

Inline drippers – Inserted into micro tubing at set intervals to allow consistent watering along the line.
Pressure compensating emitters – Water flow remains constant despite pressure changes in the line. Ensures consistent emission.
Turbulent flow emitters – Unique labyrinth pathway inside creates turbulence for a more equal distribution of water regardless of pressure.
Drip stakes – Emitter attached to a plastic stake that inserts into the ground next to each plant.

Mainline and submain pipes

Main line – Larger diameter PVC pipe that carries water from the source to different areas of the irrigation system.
Submain lines – Smaller pipes that branch off the main line to distribute water to specific garden zones.

Control valves

Valves turn water flow on and off and regulate pressure in the system:

Backflow prevention valve – Required safety valve that prevents contaminated water from siphoning back into the main water supply.
Main valve – Manual shut-off valve installed after the backflow preventer on the main water line.
Zone valves – Electrically operated valves that open to allow water into specific irrigation zones. Controlled by an irrigation controller.

Pressure regulation

Pressure regulator – Reduces high water pressure to the lower pressure required by drip irrigation to achieve the proper flow rates from emitters.
Header assembly – Contains filters and a pressure regulator in a single unit. Connects to the main water line.
Pressure compensating emitters – Drippers that ensure consistent emission despite pressure fluctuations in the system.

Filtration

Filters – Screen out dirt and debris that can clog emitters. Installed on the mainline or via a header assembly. Different mesh sizes available.
Flush end assemblies – Install at the ends of drip lines to allow flushing out of sediment.
Air vents – Release trapped air pockets that can hamper water flow due to pressure buildup.
Flush valves – Opens irrigation lines to full pressure to flush out accumulated sediment.

Irrigation controllers

Controllers automate opening and closing of zone valves according to programmed run times and schedules:

Hose-end controllers – Basic timers attached to outdoor faucets to automate watering times.
Standalone controllers – Indoor or outdoor controllers that manage multiple zone valves and program start times and run times.
Smart controllers – Advanced systems that tailor watering schedules based on weather, soil moisture levels, flow rates and other data.

Drip System Design

Careful planning of the layout and components is necessary to create an efficient drip irrigation system customized for your garden’s unique needs.

Steps for designing a drip system:

Make an outline of your garden – Sketch the shape and dimensions of each planting bed. Indicate sunny and shady areas.
Know your water source – Note location, pressure and available flow rate (GPM). Higher pressure allows more drippers.
Group plants by water needs – Plants with similar needs should be zoned together for their own valves and irrigation lines.
Lay out piping – Mainline piping should run along edges with submain lines branching off to reach all zones.
Select tubing and emitters – Choose types suited for each zone’s plant spacing, terrain and sun exposure.
Include valves and filters – Strategically place valves to control each zone. Insert filters to clean water before it enters drip lines.
Include pressure regulation – Use regulators, compensating emitters and water-pressure tolerant components for proper dripper flow rates.
Automate with controllers (optional) – Determine watering schedules and needed controller capabilities based on plant needs.

Emitter flow rate and spacing

Closely spaced plants like gardens = 0.5 to 1 gallon per hour emitters spaced every 6 to 12 inches
Row crops and shrubs = 0.5 to 2 GPH emitters spaced every 12 to 36 inches
Large trees = 1 to 4 GPH emitters spaced 2+ feet apart

Zoning by plant water needs

Group plants with similar water requirements into zones for efficient watering:

Low water plants – Native, drought tolerant, succulents
Moderate water plants – Most vegetables, herbs, perennials
High water plants – Thirsty shrubs, trees, annuals

Irrigation Schedules

Vegetables – Frequent, short cycles. 1 to 3 times per day, 15 – 30 minutes per zone.
Trees and shrubs – Infrequent, deep watering. 2 to 3 times per week, 1 – 3 hours.
Lawns – Short cycles every 2 days to keep roots moist but not soaked.

Watering Times

Clay soil = Shorter cycles, allow time for water to soak in
Sandy soil = Longer cycles, water drains quickly
Hot weather = More frequent cycles
Cool weather or rain = Water less frequently

Proper drip system design matched to your garden ensures efficient irrigation for healthy plants.

Installing a Drip Irrigation System

Installing a drip system involves connecting all the components to form water delivery lines to nourish plant roots without any leaks or clogs.

Step-by-Step Drip System Installation

Install backflow preventer – Required device connects to main water line to prevent contamination of water supply.
Connect main water line – Dig trenches and lay PVC mainline pipe from the water source out to the irrigation zones.
Install control valves – Connect zone valves to the mainline where submains will branch to different irrigation zones.
Add filter and pressure regulator – Install a filter and pressure regulator on the mainline or via header assembly after the valves.
Lay out drip tubing – Arrange drip lines along plant rows or around the root zones of individual plants.
Connect to water source – Attach drip tubing to submainlines, headers and control valves via fittings.
Flush lines – Open valves and ends of drip lines to flush out dirt and debris inside new tubing.
Connect emitters – Insert inline drippers or connect drip stakes along tubing at proper spacing next to each plant.
Test system – Turn on valves in sequence and inspect all connections, emitters and lines for leaks before burying tubing. Make repairs as needed.
Add mulch – Cover drip tubing with mulch, soil or landscape fabric to prevent damage from wildlife and weather.
Set irrigation schedule – Program controller with plant watering needs and zones. Adjust as needed with seasonal weather changes.

Proper installation ensures an efficient drip irrigation system that provides steady, reliable watering to plant roots for years to come. Be sure to winterize systems in climates with freezing temperatures.

Drip Irrigation Maintenance

Ongoing maintenance keeps drip systems working properly by preventing clogs and leaks that can reduce performance.

Drip System Maintenance Tips

Flush lines – Periodically flush drip tubing by opening ends and valves to high pressure. Flushes out dirt and buildup.
Inspect filters and emitters – Check for clogs and clean or replace filters. Remove mineral deposits from emitters.
Monitor pressure – Ensure header pressure remains stable. Adjust as needed. Add booster pumps if pressure drops.
Watch for leaks – Look for wet spots that indicate leaks in tubing connections and fittings. Repair leaks to avoid water loss.
Adjust and repair tubing – Fix kinked or damaged drip line sections. Re-space emitters for plant growth or spacing changes.
Tune watering schedules – Adjust run times and frequency for seasonal water needs and weather changes. Set automatic controllers.
Prevent wildlife damage – Use animal repellents around tubing. Bury lines deeper. Ensure protective mulch cover remains intact.
Winterize in cold climates – Drain all water from supply lines and tubing before first freeze. Insulate components like backflow preventers.

By inspecting, cleaning and repairing the drip system regularly, it will provide years of reliable service. Tune the system based on experience for optimal plant health and water savings.

Frequently Asked Questions

What are the advantages of drip irrigation?

Drip irrigation offers many benefits including water savings, disease prevention, reduced fertilizer use, automation options, and improved plant growth. Drippers apply water and nutrients directly to the plant roots which maximizes absorption while eliminating waste from runoff, evaporation and overwatering.

How often should a drip system be run?

Most plants do best with frequent, short run times of 15-45 minutes 1 to 3 times per day, especially for vegetables and in hot weather. Trees and shrubs prefer occasional deep watering for 2-4 hours, 2 to 3 times per week. Adjust schedules based on plant needs, weather, and soil type.

What size drippers and tubing should I use?

Most home gardens do well with 0.5 to 2 gallon per hour drippers spaced 6 to 18 inches apart along 1/4 to 1/2 inch tubing. Lower flow for closely spaced plants, higher for wider spacings. Submains are often 1/2 to 3/4 inch diameter. Mainlines can be 3/4 inch or larger as needed.

How deep should drip irrigation tubing be buried?

Drip lines should be covered by 2 to 4 inches of mulch or soil to prevent damage. Deeper burial can also protect from freezing. Ensure emitters remain visible for inspection and that water can penetrate soil surface.

How can I prevent clogging in drip systems?

Installing a filter on the mainline removes debris that can clog emitters. Periodically flush the drip system by opening ends of lines while water is flowing. Replace old drip tape after one growing season to prevent internal buildup.

Can drip irrigation be automated?

Yes, installing an automatic controller makes drip system operation much easier. Smart controllers adjust to weather and conditions. Zone valves allow custom watering per plant needs. Timers automate when the system turns on for hands-free operation once set.

Final Thoughts

Drip irrigation delivers direct water and nutrient absorption to plant roots for optimal growth while saving water compared to other irrigation methods. With mindful design and regular maintenance, drip systems are an efficient choice for both gardens and farms. Matching the drip components to your unique watering needs and environment will provide reliable irrigation for many years of successful gardening.