Family drip kit, 500 m²
A covered tank 1–1.5 m up, a valve, a 120-mesh filter, a 25 mm main and 8 mm dripper lines: drip irrigation for a family plot by gravity, with no pump and no power.
Build
Tier 5 · Second industrial revolution
Food
Easy to install; the work is in scheduling the water and keeping the lines clean
A day to set up the stand and tank and lay the lines
Crew 1–2
Home: Crops and soil, Level 5 · Current, level 5 of 7 in its track. Serves 1 step.
Every build on this site has hazards that injure or kill — quicklime, carbon monoxide, molten metal, collapsing ground. Read the safety notice before starting, and read this build's own failure modes below.
What it is and why this shape
Drip puts 80–90 % of the water where the roots are, against 40–50 % for flooding from earth canals (drip and sprinkler irrigation). FAO's handbook describes a kit that brings it to a family plot without a pump: a tank raised 1–1.5 m, a valve and a filter, and drip lines working at 0.1–0.2 bar; the piping for 500 m² cost about US$100–120 in 2007 (FAO, Handbook on Pressurized Irrigation Techniques, chapter 15). The weak points are the ones FAO names: without training and maintenance the lines clog and the kit lasts one or two seasons, so the filter, flushing and the schedule below are part of the build.
Tank and head, in elevation
Fig 1
Earth / subsoilTimberWater
The 500 m² plot, in plan
Fig 2
Gravel / aggregateWaterVoid / air
Keyed parts
| 1 | Tank | 200–3,000 L: a plastic barrel, an iron drum or a built tank, always covered against dirt, light and algae. |
| 2 | Stand | Holds the full tank with its base 1–1.5 m above the ground; braced, on firm footings. |
| 3 | Drain tap | At the bottom of the tank, to flush out the sediment often. |
| 4 | Tank outlet | 1 inch threaded, fixed at least 5 cm above the bottom so sediment stays in the tank. |
| 5 | Shut-off valve | 1 inch plastic gate or ball valve, connected straight to the outlet. |
| 6 | Screen filter | 1 inch plastic line filter, screen or disc, 120 mesh, after the valve. |
| 7 | Main pipe | 25 mm black PE, PN 2.5, along the middle of the plot, with quick-release compression fittings. |
| 8 | Start connectors | 8 mm barbed plastic connectors pushed into the main at the row spacing; blind plugs close spare holes. |
| 9 | Dripper lines | 8 mm PE with built-in labyrinth drippers every 30 cm, 0.5–0.7 L/h at 1 m of head; no longer than 12–15 m. |
| 10 | Tensiometer pair | At 30 % and 60 % of the root depth beside the plants in one row: irrigate when the shallow one reads 18–25 centibars. |
Specifications
| Area | 500 m², 20 × 25 m | FAO's standard kit; 250–1,000 m² depending on the crop spacing. |
| Head | 1–1.5 m of water, 0.1–0.2 bar | Raise the tank higher to make up friction in a long main. |
| Flow | about 1.1 m³/h at 1.5 m head | About 1,600 drippers at 0.65 L/h with 500 m of line. |
| Dripper lines | 8 mm, 12–15 m; or 12 mm, 25–30 m | Maximum lengths at 1 m of head on level ground. |
| Drippers | every 30 cm | 0.5–0.7 L/h at 1 m of head, 0.65–0.95 L/h at 2 m. |
| Filter | 120 mesh | Drippers need 80–160 mesh (200–100 µm). |
| Ground | slope under 0.5 % | Medium or fine soil taking in under 20 mm an hour; not very light sand. |
| Water | pH 6.5–8.4, 500–2,000 mg/L dissolved salts | Under 0.7 mg/L boron and 1.5 dS/m for strawberries and beans. |
Bill of materials
| Material | Quantity | Notes and substitutes |
|---|---|---|
| Tank, 200–3,000 L, with lid | 1 | A bigger tank needs fewer fillings: 2,750 L a day from a 200 L drum is about 14 fillings. |
| Timber or block stand for the full tank | 1 | A full 200 L drum weighs over 200 kg. |
| Drain tap and 1 inch tank outlet | 1 each | Outlet at least 5 cm above the bottom. |
| Plastic shut-off valve, 1 inch | 1 | Gate or ball. |
| Plastic screen or disc filter, 1 inch, 120 mesh | 1 | Line filter, with a spare screen. |
| Black PE pipe 25 mm, PN 2.5 | 45 m | Main; FAO's kit list. |
| Quick-release elbows, 25 mm × 1 inch and 25 mm | 1 each | Tank connection and the turn into the plot. |
| Barbed start connectors, 8 mm | 45 | One per dripper line, with spares. |
| Blind start connectors, 8 mm | 10 | To plug wrong or spare holes. |
| PE dripper line, 8 mm, drippers every 30 cm | up to 500 m | Integrated drippers with wide passages and their own filter. |
| PTFE thread tape | 1 roll | On every threaded joint. |
| Tensiometers | 2 | One shallow, one deep. |
Tools: Hole punch for the start connectors · Knife or pipe cutter · Spirit level or water level · Tape measure and string line · Bucket and watch for the catch test · Measuring jug or graduated cylinder
Construction
Choose the plot and the water
Level ground, or an even slope under 0.5 %, of medium or fine soil; FAO advises against very light sandy soil. Rows 12–24 m long. Have the water tested: pH 6.5–8.4, dissolved salts 500–2,000 mg/L; for strawberries and beans, boron under 0.7 mg/L and salinity under 1.5 dS/m. Any source that can refill the tank regularly will do: a well, a pond, a ditch.
Build the stand and set the tank
Set the tank beside the plot at the middle of the main, or in the middle of the plot, with its base 1–1.5 m above the ground on a braced stand strong enough for the full tank. Fit the drain tap at the bottom and the outlet at least 5 cm above it. Put the lid on and keep it on.
Fit the head
Screw the valve onto the outlet and the 120-mesh filter after it, with PTFE tape on every thread so nothing leaks. Connect the 25 mm main through the elbow and run it straight across the middle of the plot along the 20 m side.
Punch in the start connectors, then flush the main
Mark the rows on the main at the crop's spacing — 1.5 m for trellised tomatoes, closer for others — and push in a start connector at each, on both sides. Plug any wrong hole with a blind connector. Fill the tank, open the valve and flush the main with its end open until the water runs clear (FAO).
Lay and flush the dripper lines
Push a dripper line onto each start connector and lay it along the row, no longer than 12–15 m for 8 mm line. Open the valve and flush the lines with their ends open, then close each end by folding it back and tying it, or with an end plug.
Test the evenness
Run the kit with a full tank. Set a cup under 10 drippers from the near to the far end of the longest line for 5 minutes, measure each, and compare with the average: all within 10 % passes. A low far end means the line is too long or the head too low; scattered low drippers mean blockage (drip irrigation).
Irrigate to the plants
Water every 1–3 days: about 0.5–1 L per plant a day at first, 1–2 L as the crop sets, 3–6 L at full growth, up to 5–7 L for big crops such as watermelons late in the season; daily at the peak, and 10–20 % less at harvest (FAO). Read the tensiometers and start when the shallow one reads 18–25 centibars. A 200 L drum feeding 2,750 L a day to 500 m² runs about 2.5 hours and needs refilling about 14 times, so a bigger tank saves labour.
Keep it clean
Open the drain tap and flush out the tank's sediment often. Clean the filter screen whenever the flow drops. Flush the lines regularly and treat slime, scale and algae as drip irrigation describes. Soluble fertilizer can be dissolved in the tank (FAO).
Tolerances that matter
| Dimension | Target | Why it matters |
|---|---|---|
| Tank base | 1–1.5 m above the ground | Lower, and the far drippers get too little pressure; the kit works only by height. |
| Outlet | at least 5 cm above the tank bottom | Keeps the settled sediment out of the filter. |
| Dripper line length | no more than 12–15 m (8 mm) at 1 m of head | Longer lines lose too much pressure to friction and the far plants go short. |
| Ground slope | under 0.5 % | At such low pressure, a slope makes the downhill drippers run faster than the uphill ones. |
| Evenness | every dripper within 10 % of the average | Otherwise some plants are drowned to keep others alive. |
How this fails
A tank set too low, or a main run too far: the pressure is too weak for the last drippers.
An open tank: dirt and algae reach the filter and the drippers.
A filter never cleaned: the flow falls week by week until the crop wilts.
Leaking threaded joints without PTFE tape: water and pressure lost before the plot.
Lines too long or laid uphill: the far end dries.
Watering by the clock, not by the plants and the tensiometers: too little at the peak, too much at the start.
No maintenance: FAO reports kits lasting only one or two seasons where farmers were not trained to keep the lines clean.
How you know it worked
VerificationWith a full tank, the catch test puts every dripper within 10 % of the average, the wetted strip along each row is continuous, the joints do not leak, and the tensiometers stay between 10 and 25 centibars through the season.
Scaling and variants
1,000 m²: two kits side by side, each with its own tank (FAO). A group of farmers sharing one well can share a small pump to fill a larger tank for each. Longer rows take 12 mm dripper line, up to 25–30 m at 1 m of head. More head, from a tank set higher, makes up for a long main; the drippers give 0.65–0.95 L/h at 2 m.