Gravity Drip Irrigation: Watering Beds From a Raised Barrel
Gravity drip irrigation runs drip lines from a raised rain barrel or tank. Water flows down to the plants with no pump plus no city pressure.
The short answer
UF IFAS notes rain barrels hold 50 to 80 gallons. They need a fine screen plus a tight lid. Iowa State calls a 100 mesh filter a must, since small emitter openings clog. Colorado State notes slopes waste water as gravity pulls it downhill. Raise the barrel, filter the outlet plus check each emitter.
How does gravity drip irrigation work?
Roof water runs into the barrel through a hole in the lid, UF IFAS explains. A low valve feeds a hose or seep line. WSU Extension lists gravity fed water from a cistern or tank as one supply option.
| Part | Job | Source note |
|---|---|---|
| Screen on the lid | Blocks leaves plus insects | UF IFAS |
| Filter at the outlet | Stops emitter clogs | Iowa State: 100 mesh |
| Emitters | Drip water at roots | 1/2, 1 or 2 gallons per hour |
| Soaker line | Seeps along a row | WSU: 10 psi or less |
Source: UF IFAS, Iowa State plus WSU Extension.
How high should the barrel be?
UF IFAS notes you may want to raise the barrel so the spigot is easy to reach. No source sets a height. Iowa State notes drip systems run at a low, steady 10 psi, far under house tap pressure.
Which drip parts work at low pressure?
Colorado State notes pressure compensating emitters give the same flow over a wide pressure range. Pressure sensitive emitters flow faster as pressure rises. Space emitters 12 inches apart in sand, 18 in loam plus 24 in clay.
How to: step by step
- Put the barrel on a firm, level stand.
- Fit a screen filter at the outlet.
- Run main tubing toward the bed.
- Add emitters or a soaker line.
- Open the valve plus check flow at each plant.
- Flush lines plus clean the filter often.
Troubleshooting
Weak flow at the far end: line too long. Shorten it or raise the barrel.
Dry plants: clogged emitters. Clean the filter plus flush the lines.
Barrel overflows: heavy rain. UF IFAS advises disconnecting the downspout when you are away.
Read garden microclimates, planning an outdoor garden layout plus underwatering. Kind Seed Co also stocks cannabis seeds.
Sources
- Rain barrels, UF IFAS Gardening Solutions
- Drip irrigation for home gardens, Colorado State University Extension
- Designing a drip irrigation system, WSU Extension
- Using drip irrigation in the garden, Iowa State University Extension and Outreach
FAQ
Can gravity drip run on a timer?
Iowa State notes a water timer can go between the filter plus the gate valve. Check that the timer you pick works at the low pressure a barrel gives.
How do I stop mosquitoes in a rain barrel?
UF IFAS advises a lid that fits tight plus a mesh screen. Always cover the barrel to block mosquitoes plus leaves.
Will gravity drip work on a slope?
Colorado State notes slopes are hard to water because gravity pulls water downhill, causing runoff. Pressure compensating emitters even out the flow.
What size barrel do I need?
UF IFAS notes barrels are often 50 to 80 gallons. About 600 gallons can run off 1,000 square feet of roof per inch of rain, so you may want more than one.
Do I need a filter on a rain barrel drip line?
Yes. Iowa State calls a 100 mesh screen filter a must, since unfiltered emitters clog plus plants dry out.
