The size on the label is not the size
Half-inch drip tubing is sized nominally, and the real inside and outside diameters differ between makers, as DripWorks points out. DIG lists three sizes, each taking its own color of compression fitting: .520 × .620, .600 × .700 and .620 × .710 inch (inside × outside). Rain Bird sells 0.63 inch outside diameter as standard and 0.70 or 0.71 inch as heavy duty, and Raindrip sells .600 × .700 inch tubing under a 5/8-inch label. Match fittings to the measured size, not the label.
Sizes by maker
| Maker | Inside × outside diameter | Notes |
|---|---|---|
| DIG | .520 × .620 in | Green-insert compression fittings |
| DIG, DripWorks, Raindrip | .600 × .700 in | DIG: black-insert fittings; Raindrip labels it 5/8 in |
| DIG | .620 × .710 in | Blue-insert fittings |
| Rain Bird | 0.63 in outside (standard); 0.70 or 0.71 in (heavy duty) | Rain Bird says 0.630 in tubing needs 0.630 fittings |
How far and how much
Rain Bird says ½-inch tubing should not run longer than 250 feet in any one direction. DIG recommends no more than 220 gallons per hour on a single run of its .600 × .700 inch tubing. The drip parts calculator adds up your emitters’ flow and compares it with that figure.
When it isn’t working
Weak or no flow at the end of the line. DIG says to check first for a clogged dripper or a faulty pressure regulator, then for too many drippers on the line: it recommends no more than 220 gallons per hour on one line.
A cut or split. Rain Bird cuts out the damaged section and joins new tubing with barbed couplings or barbed tees.
In the kits we cover
The Rain Bird GARDENKIT uses 25 feet of ¼-inch distribution tubing rather than ½-inch. The Epic Starter Kit has 50 feet of 16 mm poly main tubing; Epic does not say whether 16 mm is the inside or outside diameter, so use Epic’s own fittings with it.