A Short Course in Drip Irrigation

Pressure gauge

This is a topic I have been meaning to write about since we finished installing the drip irrigation system last May. It took a decent amount of research since none of us had experience in setting up anything like this. We knew that we wanted to capture rain to utilize as our water source for the system, so that was the first step in construction. That part was pretty straight forward and meant putting up 60 feet of gutter on a nearby shed and connecting the runoff to the two cisterns we already had in place. Our current cistern capacity is roughly 600 gallons. Next, we needed to figure out how to transfer water from the cisterns to the hops and use drip irrigation to control distribution. Little did we know just how many options for pumps, hoses, fittings, emitters, etc. existed. We shopped at berryhilldrip.com, which is out of Virginia, for the bulk of the supplies. Feeling a bit overwhelmed by the catalog we called their customer support which was very helpful in describing the different options and helping us narrow things down. They even searched out an article for us about a hop farm out west which described a little about what they were using for their drip system. This post is a bit more of a technical read, but we hope it is helpful and a time saver for those looking to do a similar setup. Keep in mind that the system described was designed to deliver water throughout five 120-foot rows of hops which are spaced roughly 40 inches apart in the row. Any changes to these dimensions may affect how you will want to approach your design.

Red valve fitting connects main to RAM

Red valve fitting connects main to RAM

To move water from the cistern through the system we went with a 1/10 horsepower electric water pump. The pump pulls water from the cisterns, which flows through a separate filter to remove any dirt/debris, and then connects to the main line of the system. The main line is made of 3/4″ poly tubing. The main line then connects to the drip line (hose) which is 17mm RAM (aka, heavywall dripperline). The RAM has emitters, which are basically pin-sized openings in the line, built in and spaced every 2 feet. We went with 2-foot spacing, but other options do exist. RAM is a bit more expensive than some of the other drip line hoses, but it is built to last for several seasons and is pretty heavy duty (intended for perennial crops). The connection of the main line to the drip line is made with a valve fitting – one connection for each row. This allows each row to be turned on/off individually. The cost was slightly more to have the value in the fitting, but the added control was worth the few extra dollars. Finally, the end of each row and the end of the main line were simply capped to stop flow and thus create pressure which forces water to exit the system through the emitters.

Our system runs at about 7-8 psi, which is about as low as you want to go for proper functioning using RAM. A slightly larger pump may have been a better choice in case we are to expand. The emitters are rated to dispense water at a rate of 0.42 gallons per hour. We used 600 feet of drip line in the system, which means there are 300 emitters (one emitter every 2 feet). Multiply that times 0.42 gallons per hour and we are dispensing 126 gallons of water per hour across 180 plants. Pretty cool, huh?!!! Below is a map to help visualize the description of the system. If you have any questions or would like even more info please post in the comments below. Enjoy!!

– Justin



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