There are lots of choices to make when it comes to drip irrigation drippers (sometimes called emitters). To choose the best one for your project, you have to take into account several factors. These factors include but are not limited to pressure compensating (pc) vs. non pressure compensating, dirty or hard water, elevation changes, and varying water requirements between plants. In this guide we will discuss each of these factors as well as several other considerations in more detail.
Pressure Compensating vs. Non Pressure Compensating
A pressure compensating dripper will deliver the same amount of water to each plant regardless of changes in pressure throughout the drip irrigation system. A non pressure compensating dripper will not compensate for the pressure change, and thus not all your plants will receive the same amount of water.
What might cause a rise or drop in pressure in a drip irrigation system? Very long runs of tubing at or above the gallon per hour capacity for that tubing size and/or changes in elevation. If your system is using long runs of tubing or is installed over terrain that has elevation changes, then we recommend a pressure compensating drip emitter.
If You Have Dirty or Hard Water
If your water is coming from a well, pond, rain barrel, or other source that collects debris, then we strongly recommend a cleanable dripper. This recommendation also goes for anyone that has hard water and sees deposits build up. Cleanable drippers can be opened up and cleaned. If you were to use a dripper that was not cleanable, and it were to get clogged, you would have to replace the entire dripper, since there is no way to clean it. Cleanable drippers allow for the head of the dripper to be unscrewed from the base of the dripper so that the orifice can be cleaned of any debris that is blocking the flow of water.
Slopes and Elevation Changes
Slopes and elevation changes can change the pressure within a drip irrigation system. This can alter the amount of water that is emitted from each dripper in a system. If this is not a concern for you, then you can use any dripper you like. However, if you are watering on a slope and you wish for all the plants in the system to receive the same amount of water, then we recommend using a pressure compensating dripper.
Attaching Drippers to PVC Pipe
For anyone looking to place emitters directly into PVC, a threaded emitter is needed. The barbed emitters will not connect directly to PVC. Our threaded emitters and threaded ¼” fittings are all on 10/32 threads. To use these, you would simply pre-tap your PVC with the appropriate sized drill bit and screw in the emitter or fitting. If you want to use a barbed dripper with PVC, you can use our 1/4" Barb Adapter x 10-32 Thread. You would pre-tap the PVC, screw in the threads, and then attach a length of microtubing and insert the barbed dripper at the end of the microtubing.
Drippers for Hanging Baskets
Any emitter could work for this application. However, there are a few things to consider. First, it is critical to have the emitter centered over the basket. For this we recommend using a rigid riser instead of microtubing (microtubing can curl and place the dripper to the side of the basket). To insert an emitter into a rigid riser, a threaded dripper is needed, so a dripper on 10/32 threads is needed. Secondly, hanging baskets drain very quickly, so a dripper that can emit a lot of water quickly is needed. We have found the perfect dripper to be our adjustable dripper on 10/32 threads. As a bonus, the dripper can be adjusted all the way off if needed.
Recommended Dripper: 360 Adjustable Dripper on Threads
Watering schedules for plants in containers will be different from those for plants in the ground. The soil most often used in containers is potting soil, and potting soil has little to no capillary action. What this means is that there is very little horizontal movement of the water from the top to the bottom of the container. In addition, plant roots in containers dry out much faster than plant roots that are planted in the ground. We have found that a typical watering schedule for containers will look something like 2–4 times per day for 1–2 minutes each time.
When choosing an emitter for your containers, you will want to take the above information into consideration. You can use any dripper that we sell, but depending on your choice of emitter, you may need to add additional drippers to ensure good water coverage. You may also need to add a stake to anchor the emitters in place so they do not fall out of the pot.
The main goal in choosing an emitter is to get good root zone coverage. This is true regardless of where the plant is planted. As was mentioned previously, potting soil has poor capillary action, so you will only get about a 6” wet pattern from each drip point. If your pot is small, then one button dripper is great, but if your pot is large, you will need to determine how many drip points you will need for good root coverage.
We sell drip spikes that have a dripper built into the stake, which can translate into real time savings if you have a lot of pots to irrigate. For a container that is 6–8 inches, one dripper should work. For larger pots you may need to place more than one dripper in the container to adequately water the plant. If the pot is very large and has a water hungry-plant inside, then we would recommend one of our adjustable drippers on a stake.
Balancing a Drip Irrigation System When Using Adjustable Drippers
One of the largest challenges in setting up a drip irrigation system is balancing the watering requirements of a variety of plants. This can be done one of two ways: you can either create separate watering zones for like plants, or you can select different drip emitters based on the plants’ watering requirements for an area.
For example, let’s say you have two plants on the same watering line; one plant requires moderately moist soil, and the other plant requires consistent moisture. In this case we might recommend an emitter such as a .5 GPH (gallons per hour) button dripper for the first plant and an adjustable dripper for the second plant. The button dripper will only deliver the regulated amount, in this case a half a gallon per hour, but the adjustable dripper, depending on the model chosen, could deliver up to 20 GPH. These drippers are fully adjustable by simply twisting the top of the dripper from closed to fully opened and all points in between.
Adjustable drippers come in maximum flow rates of 10 and 20 GPH. One word of caution here is that these do eat up a lot of water, so try to use them sparingly, as too many may overtax your system. The end result is that by matching the dripper to the plants’ watering requirements, you are able to better water plants with different watering requirements all on the same line.
Recommended Drippers: Adjustable Dripper on 5" Stake, Adjustable Vortex Sprayer on 5" Stake, Adjustable Mini Bubbler on 5" Stake, 360 Adjustable Dripper on Threads, Mini Bubbler on Threads, Vortex Sprayer on Threads, or 360 Adjustable Dripper on Barb