What Length Can Drip Tubing Be? How Many Gallons Can it Handle?

Recently I saw quarter inch blank tubing with a length of  over 80 feet! Of course this is too long for quarter inch tubing. But how long is acceptable? How long can drip tubing be extended and still work? How many gallons can a length of drip tubing be designed to handle?

I put this original table together just to answer those questions.

"Half inch" drip tubing with embedded emitters

Approximate Water Capacity for Different-Sized Drip Tubing

Hose Size1 (in)	Hose Size2 (ID) (mm)	OD3 (in)	ID4 (in)	Wall Thickness5 (in)	Max Flow  @ 5 fps6 (gph)	Max Flow    @ 1.5 mps (Lph)	Max Run7 (ft/m)	PSI Loss8 (per 100 ft/30m)
¼ inch	4.3mm	.25	.17	.05 – 1.0	30	120	30/9.1	15.0
½ inch	17mm	.67	.62	.05 -.10	240	960	200/61	9.6
¾ inch	20.8mm	.92	.82	.10	320	1280	480/146.3	5.8
1 inch	26.7mm	1.15	1.05	.10	720	2880	960/292	3.8

¹ Common generic terms for hose sizes; quarter-inch, half-inch, three-quarter inch and one inch. A hose size can have several similar sizes that may be called “half inch”. Always buy name brand drip tubing, blank tubing and fittings for consistency and match their sizes.

² Hose size is not yet standardized. For instance, half inch hose is available in 15, 16 and 17mm internal diameters (ID). The ID will affect the PSI Loss of water pressure inside the tubing and affect its flow rate. Hose size for carrying water is always based on ID (Internal Diameter). Outside diameter (OD) may be used for PE fittings that grasp the outside of the PE tubing such as compression fittings. Sizes you find may not be exact but approximations. Always match your fittings to the ID or OD of the tubing.

³ Outside Diameter (OD) of the PE tubing.

⁴ Internal Diameter (ID) of the PE tubing.

⁵ “Wall Thickness” can vary with different PE tubing. Some PE tubing has thinner walls than others. Different sized drip tubing (e.g., half inch tubing) can affect how much PSI can be used before it fails. Thinner walled tubing is more appropriate for gravity fed systems or lower PSI.

⁶ Five feet per second (5 fps) is the max speed (velocity) water is designed to travel in piping or tubing for pressurized irrigation systems. Velocities greater than this will contribute to “water hammer” , fitting failure, and pipe/tubes bursting.

⁷ “Maximum Run” is the maximum length PE tubing is installed due to a significant loss of water pressure when it is flowing (PSI Loss).

⁸ “PSI Loss” is the loss of water pressure (PSI) because of the friction (rubbing) water has against the inside of tubing. The "PSI Loss" is measured at the end of a distance that the water might flow and typically standardized at 100 feet (30 meters).