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  • NutraDrip Irrigation

Flushing Components for a NutraDrip SDI system

When observing the NutraDrip team installing SDI, you may wonder why they pull out bright cans of spray paint and seem to randomly color the pipes distinct colors. There is a method to the madness: the color of the pipe is important. NutraDrip color codes the flushing components of a drip system to ensure service work and maintenance is as pain free as possible. The different flush components in a system are important to its operation, maintenance, and longevity.  

If we start at the “beginning” of a drip system, the first colored pipe one will encounter is blue. Blue pipes are on the submain side of the field and are on the feed line side of the drip system. Water enters each zone from the blue pipes and valves. It passes the continuous air vent and flows through the zone control valve. The control valves are meant to regulate the water pressure and ensure that high pressures do not damage the drip tape.  To check the pressure of a zone, use a pressure gauge on the shrader valve after the control valve. The correct pressure will be different for each zone, so check the drip system design to see what pressure each zone should be at when running. The valve is usually quiet unless it is regulating water flow. If you are questioning if it is running, you can remove the spaghetti tubing at the top of the control valve. Water will come out the top of the valve if it is regulating the pressure.   

Red pipes, also known as submain flushes, are located at the end of a submain (which is the pipe in the ground that feeds all the drip tape). These pipes are on the same side of the drip system as the blue submain feed pipes. The red pipes mark the end of the drip line zone and are used to flush the PVC manifold (pipeline) to which all the drip lines are connected. The sole purpose of this valve is to flush out the submain pipe that all the drip tape is connected to. There is another shrader valve to check the pressure on this side of the zone, as well. If you open the end valve, you may get dirty water, depending on your water quality and how long it has been since it was flushed out. Within 10-15 seconds the submain should be cleaned out and the water will be clean. 

The orange pipes are flush valves. These are on the ends of the drip tape and are used to flush out the drip tape. SDI (subsurface drip irrigation) systems are typically designed to irrigate from top to bottom (higher to lower elevation), with more flush valves positioned at the lower elevations of the field. Each irrigation zone typically has two flush valves, but only one should be opened at a time to maintain the correct water velocity of 1 foot per second, ensuring effective cleaning of the drip line. When flushing, the water should be clear initially, but if it has not been flushed in a while, dirt, sludge, and iron may discolor the water after a little bit. This maintenance step helps monitor water quality. It is normal to see particles being flushed out, but if you notice any significant changes in the water since the last time it was flushed, we recommend doing a water sample to see if there are any changes.  

During flushing, it is crucial to maintain high enough pressure at the valve. If the system is designed for 25 pounds of pressure and too many flush valves are opened, the pressure will drop significantly, and the pump will struggle to keep up.  

As you can see, color is important to note when checking the flushing components of a NutraDrip SDI system. Blue pipes are control valves for zones, red pipes are flush valves for the submain, and orange pipes are flush valves for the drip tape at the “end” of the system. Each of these is important in the functioning and maintenance of a drip system. Proper maintenance of flush velocities and pressures is essential for effective cleaning of the drip line and longevity of an SDI system. If you every have any questions or concerns about your system, please reach out to your sales rep, or Joel Schesser, service manager ( 

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