I've been tasked with setting up a drip system, and I'm at a loss of how to go about it. My only source of water is from a 3/4" garden valve. I am planting 250 plants, and ideally 250 emitters will go with them. They will spaced equally apart lengthwise (3.2') along an 800' stretch of ground. Each plant will be 2' from the center line of the 800' planting length, with each successive plant on the opposite side of the center line. Assuming I use 1' spaghetti tubing for each emitter, I would need about 1600 ft. of drip line. From what I've read, 1/2" drip tube will only fly for about 300 ft. What would be a good way to go about this? I was planning on running 1" poly pipe along the 800' length, then possibly running 1/2" drip line from that at certain intervals. Any suggestions would be wonderful.
1 Answer
Generically, go with large diameter pipe. Specifically, you'd need to run calculations based on water flow rate, pipe size, and dynamic head (pressure loss due to flow rate) against the available input pressure at flow, and the acceptable minimum and maximum pressure for the drip emitters.
So, you have 250 emitters - but at what flow rate per emitter? If, say, you have a gallon per hour, then you know that flow from the supply will be 250 gallons per hour, or just over 4 gallons per minute, and you can use that number to look at head pressure lost in 100 feet of various sizes of pipe. At each stage where you have fewer emitters remaining the flow rate drops, so you COULD reduce pipe size as you get further from the supply, but that balances "possibly cheaper pipe" .vs. "possible bulk savings on one long section of pipe", as well as needing reducing fittings, etc. with the multi-size deal. The large pipe will definitely be oversized at the far end...
You may also need or get a price advantage from (you'll see when you run calculations) running two parallel suplies each supporting 125 emitters rather than a single supply with 250. It will depend in part on pipe prices WRT size.
