What it is
Water delivered slow, low, and exactly where the roots are.
Overhead sprinklers wet everything: leaves, paths, the air. Application efficiency lands between 50 and 65 percent. On a hot, windy day you lose 40 to 50 percent of your output before a drop hits soil.
Drip skips all of that. Water seeps in at the base of each plant, slow enough to soak instead of run. Efficiency: 90 to 95 percent. The soil between plants stays dry. Weeds stay quiet. Leaves stay dry, which starves powdery mildew, downy mildew, and early blight of the wet foliage they need.
Why it works
A garden switched from sprinklers to drip cuts water use by 30 to 50 percent with the same yield, sometimes better.
When the source is a finite rainwater tank, that gain extends every storage day you have. Stack mulch over the lines and the whole system can use 60 to 70 percent less water than an unmulched sprinkler setup.
That is the headline. Now the build.
Build it
Five parts in series. Source, filter, pressure regulator (if needed), mainline, laterals with emitters.
The source. Tap, pump, or gravity-fed tank. Drip and gravity are made for each other. Most emitters run happily at 0.5 to 1.5 bar. Many work down to 0.3 bar, which is three metres of head. A tank on a stand drives the whole garden with no pump and no power.
The filter. This is the part people skip and regret. Emitter orifices sit at 0.5 to 1.5 mm and clog on sediment, biofilm, and grit. Install a 120 to 150 mesh screen or disc filter upstream of the mainline. For rainwater, choose a disc filter. It handles tannins and organic matter better and cleans faster.
Mainline and laterals. Mainline is 19 or 25 mm polyethylene from source to bed. Laterals are 13 or 16 mm running along the rows. Emitters come in two flavours: inline drippers built into the tubing at fixed spacing, and punch-in drippers you place by hand. Inline drip tape is cheapest for row crops. Punch-ins win for mixed plantings on irregular spacing.
Design it
Match emitter flow and spacing to your soil and your plants. The water has to soak, not pond.
Flow rate. Standard emitters run at 2, 4, or 8 litres per hour. Sand drinks fast but spreads narrow, so use 2 L/h emitters at 20 to 30 cm spacing. Clay drinks slow but spreads wide, so 4 L/h at 40 to 50 cm works. Loam forgives almost anything.
Pressure. Long thin tubing loses pressure to friction. If the far end runs weaker than the near end, your irrigation is uneven. Keep lateral runs under 60 metres for 16 mm tubing. Connect laterals to the mainline at the centre, not the end, so pressure equalises across both halves.
Runtime. Worked example. A bed wants 5 L per square metre per day. You have 2 L/h emitters at 30 cm spacing on rows 40 cm apart. That is roughly 8 emitters per square metre, delivering 16 L per square metre per hour. Run for 20 minutes. A battery timer at the tap does the rest.
Tend it
Drip is low maintenance, not no maintenance. Two jobs keep a system alive: clean the filter, flush the lines.
Pull the filter every two to four weeks in the irrigation season. Rinse it. Reassemble. For disc filters, twist the stack apart and spray between the discs. Five minutes, and you avoid the cascade of clogged emitters that follows neglect.
Flush the laterals by opening the end caps and running the system for 30 to 60 seconds at the start of the season, the end, and once mid-season if you are pulling from rainwater or a sediment-heavy dam. If an emitter still clogs, soak it in white vinegar diluted 1:3 with water for 30 minutes, or pull it and punch a new one.
UV is the slow killer. Bare polyethylene goes brittle in direct sun within two to five years. Run the lines under mulch and the same tubing lasts indefinitely. The mulch also shades the wetted zone, blocking evaporation. Drip plus mulch is the most water-efficient surface irrigation method going.
See also
- Gravity-Fed Systems. Power drip with no pump.
- Mulching for Moisture. The partner that doubles your efficiency.
- Wicking Beds. Self-watering raised beds, an alternative approach.
- Ollas. Clay pot irrigation, ancient and quiet.
- Tank Sizing. Match storage to drip demand.
- Watering Timing. When to run the system, not just how.