An economic obstacle to greater use of drip irrigation in the USA?

LawnGenie valve does not shut off in a drip irrigation system on steep slope

• I have a drip irrigation system installed on a steep slope. The manufacturer of the valve (LawnGenie standard plastic green valve bought at Home Depot) recommends that the highest place emitter should not be more than 6 inches above the level of the valve. I have the opposite problem - the lowest place emitter is at least 10 feet below the level of the valve. When the outflow line is empty (i.e. there is only air in it) the valve operates as expected. Once the line waters and the valve shuts off, the water continues to drip out of the emitters. It is as if the water in the outflow line exerted a sucking effect on the valve and it would remain open for that reason. I called the Toro helpline but the person could not even understand the problem. I sent an email to the company but all I got was a boilerplate response. My actual question is this: short of cutting up the main line and placing the valve in level with the outflow line (which would be very cumbersome in my situation) is there any other solution, specifically a device that empties the line once the watering is over or some valve that would prevent outflow under these circumstances. TIA for your help.

• Answer:

  Hello sandy_yago, I am not an expert on drip irrigation systems and have never installed one. However, I do know something about hydraulics. I am very surprised that the Lawn Genie experts were not able to answer your question. At first I didn't understand what the term "anti-siphon" meant in the valve description. I assumed that it meant the valve prevented siphoning of water to the sprinkler heads after the syatem shuts off. After reading some on the Lawn Genie website I determined that I was wrong. The "anti-siphon" feature prevents water from siphoning back into your home water system should should there be a loss of pressure (backflow prevention). Your problem is exactly the opposite. When the system shuts off water gravity feeds the sprinkler heads until all water has drained from the system. Lawn Genie does not address this problem except for telling you to not install a sprinkler head (emitter) more than 6 inches lower than the valve. I searched for an inline check valve to install down stream from the Model 54000 valve and found one on the Rain Bird website: http://www.rainbird.com/drip/products/control/check_valves.htm Check Valves Control Zone Components Features & Benefits: Prevents water from draining upstream of check valve or back into valve box. Use with a Back Flush Filter when filter is at a lower elevation than the rest of the system. Operating Ranges and Specifications: Pressure: 20 to 120 psi (1,4 to 8,3 bars) Threads: - CV-075: 3/4" FPT x 3/4" FPT - CV-100: 1" FPT x 1" FPT Models: CV-075 CV-100 Rain Bird does allow for your problem and the 3/4 inch version of the valve could be exactly what you need. The reason I say could be is that they don't say what the opening pressure rating is for the valve. I assume that since they show the operating range is from 20 to 120 psi that the valve will hold against 20 psi of siphoning pressure which is plenty for your layout. I am sure that your local Rain Bird dealer can answer that question for you and recommend another check valve if this one is not adequate. With your 10 foot elevation difference you need a valve rated for at least 5 psi. The check valve needs to be mounted immediately after the Model 54000 valve with the flow arrow pointing toward the emitter (down stream). Then when the system shuts off the check valve will close and hold water in the line preventing additional flow. This is good for another reason also. It prevents a water hammer situation whan the line is dry and water rushes in as the system comes on. I think I have covered everything, but please ask for a clarification if I haven't. Good luck, Redhoss