How do I set up drip irrigation in a garden?

Designing a simple gravity or mains-fed drip system that reaches roots rather than leaves, and the timer and filter details that decide whether it keeps working.

Difficulty: intermediate
Time: 3 hr
Read: 4 min

Short answer

Run a 13mm supply pipe along the beds, punch in 4mm micro-tube spurs to each plant, and add a pressure reducer, a filter and a battery timer at the tap. Water early in the morning, for longer and less often than you think.

A drip system pays for itself in containers and vegetable beds, where hand watering is a daily chore and inconsistency causes split tomatoes, bolted lettuce and blossom end rot. It is much less useful on established borders, which mostly do not need watering at all.

What you'll need

13mm supply pipe
4mm micro-tubing and drippers
Pressure reducer
Filter
Battery tap timer
Hole punch tool
End stops and connectors

Step by step

Decide what actually needs it.Containers, hanging baskets, greenhouse borders and vegetable beds. Established shrubs and trees in the ground are better served by a mulch and an occasional deep soak.
Fit a filter and pressure reducer at the tap.Drippers block with grit and burst at mains pressure. Both fittings are cheap and both are the difference between a system that lasts years and one that fails in a month.
Fit a backflow preventer if connecting to mains.Water regulations require protection against back-siphonage from a garden system into the mains supply. Most outdoor tap connectors include one; check yours does.
Lay the 13mm supply pipe as a spine.Along the bed or behind the containers, held down with pegs. Warm it in the sun before laying so it uncoils and lies flat.
Punch and insert micro-tube spurs.Use the proper hole punch, insert the 4mm tube barb firmly, and run it to the plant. Blank plugs seal any hole you punch in the wrong place.
Match the dripper to the plant.Pressure-compensating drippers give the same flow along the whole run, which matters on a long line or a slope. Adjustable drippers let you give a large pot more than a small one.
Use soaker or porous hose in vegetable rows.A row of carrots or beans is better served by a porous hose along the row than by individual drippers.
Set a timer for early morning.A battery timer at the tap. Early morning is best: the plants have water before the heat, and foliage does not sit wet overnight.
Run it long and infrequently.A long slow soak two or three times a week drives roots down. Short daily bursts keep roots at the surface and make plants more vulnerable, not less.
Check it is actually delivering.Run it and walk the line. Blocked drippers, popped connectors and split tube are common and invisible unless you look.
Drain and store before winter.Water left in the pipe freezes and splits it. Disconnect, drain, and bring the timer indoors.

Tips

The filter is the component that decides how long the system lasts.
Early morning, long and infrequent. Short daily bursts train shallow roots.
Walk the line with the system running once a fortnight — blocked drippers are invisible from the house.

Common mistakes

Connecting straight to a mains tap with no pressure reducer — Mains pressure blows the fittings off the pipe and forces water out of the drippers far faster than the soil can absorb it. A reducer costs very little.
Setting the timer to run for ten minutes every morning — It wets the top of the compost only. Roots follow the water, so shallow watering produces shallow roots and a plant that collapses the first day the system fails.

If it doesn't work

Some drippers not flowing

Cause: Blocked with grit or algae — Fix: Fit or clean the filter, flush the line by removing the end stop, and replace blocked drippers.

Fittings blowing off

Cause: Too much pressure — Fix: Fit a pressure reducer, and warm the pipe before pushing fittings in so they seat properly.

Far end of the run getting less water

Cause: Pressure drop along a long line — Fix: Use pressure-compensating drippers, or split the system into two shorter runs.

Plants still wilting

Cause: Run time too short — Fix: Increase duration substantially and reduce frequency. Dig down and check how deep the water actually reaches.

Questions people ask

Can I run a drip system from a water butt?

Yes, but gravity gives very low pressure. Use a butt-specific gravity-fed kit with large-bore drippers, keep the butt raised, and expect slow delivery rather than a timed burst.

How long should the system run for?

Long enough to wet the root zone properly — often forty-five minutes to an hour on a bed, two or three times a week, rather than a few minutes daily. Dig down and check.

Do I need to take it up in winter?

Drain the pipework and disconnect the timer and any fittings holding water. The pipe itself can usually stay in place if it is drained.