Gallons per Hour from Drip Tubing

Q. How many gallons of water can be used from half inch drip tubing without running into problems? ¾ inch?

The maximum water flow at 5 ft./s in half inch drip tubing is about 240 gallons per hour (gph) while three-quarter inch drip tubing will carry about 320 gallons per hour (gph). Of course the pressure is anywhere from 25 to 35 psi. 

A. Professionals use several different names. I call these types of tubing either “blank tubing” or “drip tubing”. Both types of tubing come in either half inch or three-quarter inch diameters. “Blank tubing” doesn’t have any emitters built into it.  Blank tubing is either made to carry water to a new location or have drip emitters “punched” into them at different locations.

Drip tubing has emitters built into the walls of either half inch or three-quarter inch plastic tubes. All the emitters are the same size and space the same distance apart. Emitters can range from 12 inches to several feet apart. If the correct pressure is applied to the water, a consistent amount of water comes out of these emitters. Blank drip tubing on the other hand has no emitters built into the sidewalls. It's major purpose is the transport of water from one place to another.

            In 100 feet of tubing, the half inch blank tubing (drip and blank) can handle about 250 gallons in one hour. The three-quarter inch tubing can carry more water than half inch tubing. It can handle about 480 gallons of water, total, before you should stop. The amount of water to use has to be tallied or calculated for each “run” of tubing from an irrigation valve.

Another purpose of blank tubing is to put drip emitters into it. This can be done directly, as in the picture, or they can be connected to the blank tubing by quarter inch quarter inch blank tubing.

            Individual drip emitters are usually inserted into “blank tubing”. These inserts either are directly inserted into the blank tubing or connected to it with quarter inch tubing. “Blank tubing” is less expensive than “drip tubing” because of the embedded drip emitters in “drip tubing”. Make sure fittings used are the same size as the tubing (there are three nearly identical sizes of half inch tubing!). Buy fittings from the same manufacturer as the tubing used.

These are accessories called "barbed fittings". These fittings fit inside the tubing and keep tubing from coming apart when normal drip irrigation pressures from pressure regulators are used.