How many drippers should you use?

Deciding on the number of drippers to use is part science, part math, and partly a judgment call. Remember that you must wet at least 60% of the plant's root zone. When unsure of the number of drippers or TOP outlets needed, always use more. You must find the proper balance based on the formula and actual site conditions. You also need to be aware of the number of drippers or TOP outlets to use, If you have a 4 gph dripper or one TOP 3.3 gph outlet watering a plant, and it plugs and stops working, what will happen to your plant? On the other hand, if you have 4 1 gph drippers or four TOP 1 gph outlets the plant has a better chance to survive.

Formula to determine the number of drippers to be used per plant

Formula # 2

Example: Our plant root zone area is 78.5 sq.ft. If we have sandy soil we can see from the A4 table that we can expect 7-13 sq. ft of wetted area from a 1 gph dripper. Let's stay on the conservative side and use 10 sq. ft. of wetted area. The number of drippers per # 2 formula for the 10 ft tree is 7.8 -1 gph drippers. Let's round it to 8 drippers. The last step is to use formula # 3 to determine how long we turn the water on each day. Formula # 3

Formula # 2

A4 Wetting Pattern of drip emitter to be used in point source formula  Soil type  Dripper flow rates GPH  Wetted area (ft)  Wetted area (sq. ft)  Sandy  0.5  1-3  1-7  Sandy  1.0 or 2.0  3-4  7-13  Loam  0.5  2-4  2-13  Loam 1.0 or 2.0  3-5 7-20  Clay 0.5  2-3  3-7  Clay  1.0 or 2.0  3-5  7-16  Clay  4.0  4-6  13-28

Last formula, # 3 determining system run time per day

Formula # 3    Formula # 3

Example: If the tree needs 12 gallon per day ( plant water requirement from formula # 1) divided by the number of drippers ( from formula # 2) x the drippers flow rate, and you get a run time of 1.5 hours every day, or 3 hours every two days.

Conclusion: We will turn the water on for 1.5 hours every day using 8 drippers at a flow rate of 1 gallon per hour.