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I have assembled a small DIY drip-irrigation system for my terrace garden. Please have a look at the attached image. I switch on a small pump to start the drip-irrigation system and then switch it off. But even after that, the water keeps flowing through the system and stops only when I physically lift the pump out of water.

How can I stop this water flow without requiring any physical action?

drip-irrigation-system.jpg

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  • $\begingroup$ Make sure the water level in the tank never exceeds the plant height. Dig the tank into the soil somewhat so tank and plants aren't at the same level. $\endgroup$
    – Gert
    Apr 25 '16 at 15:52
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    $\begingroup$ Why not make use of the syphon and remove the pump? Keep the water level above plant height and install a tap to regulate flow or stop it completely. If you want to be fancy you can automate the tap and put it on a timer. Without a sensor, for a constant flow you need a constant 'head' of water, so you would need a drip-feed into the tank and an overflow to keep the water level constant. $\endgroup$ Apr 25 '16 at 17:18
  • $\begingroup$ @sammygerbil, this is kept on the terrace and I do not want to go and operate the tap. I understand that I can put a automated timer to start and stop the water flow. But, I am looking for another way to stop the water flow as described in the diagram. $\endgroup$
    – javed
    Apr 26 '16 at 6:32
  • $\begingroup$ Google for "vacuum breaker." Install it at the highest point in the line. $\endgroup$ Jul 20 '16 at 13:59
  • $\begingroup$ Can you just put a valve in the pipe? Or if the pipe is a rubber hose, just fold it in two and tie it. $\endgroup$ Jan 4 '17 at 1:24
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The immersed pump my son used to water the garden from a rain water cistern has a top outlet over the level of the cistern water, dripping on a rose bush planted there. When the pump is turned off, this top small fountain head can be heard sucking air while the lower line empties.

I always check that the top drip works when the pump is on , otherwise there will be a siphon that will stop only when the cistern empties :).

So you just have to install a , maybe useless , drip over the height of the water,( and put a flower pot there :))

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  • $\begingroup$ actually the simplest is to put a faucet at the top of your diagram. When you turn off the pump open the faucet, and that will do the same trick as a drip over the water level. close it before you start the pump again. My son's trick is for automatic watering. $\endgroup$
    – anna v
    Jan 4 '17 at 7:08
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I would put a small "T" in the water line at the top of my tank, above the water line. Position it to pump water back in your tank when running. when the pump stops it should break the vacuum. Water goes back to your tank so it is not wasted.

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Beside my previous answer to use a check valve, another simple way is to extend the vertical line from the pump several inches above the top of the tank and at the top of that line turn the line 180 degrees downward. Install a tee connection in that vertical line at the point where you branch off to direct water to the plant pots and connect the line to the plant pots to it. When pump is turned on, water will flow from the pump and back into the tank due to the 180 degree return line and at the same time water will flow to the plant pots through the horizontal leg of the tee. When the pump is shut off, there will be no siphon effect.

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Can you just put a valve in the pipe? Or if the pipe is a rubber hose, just fold it in two and tie it. The kink in the hose will block it.

BTW, if you do that, after you start it you don't even need the water pump. You can just open the valve.

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Another alternative: make sure that you are using a positive displacement pump. When such a pump shuts off, water cannot keep flowing through the pump.

Another possibility (from 9/02/2018): install a "T" at the point where the pump discharge line first goes horizontal. Turn one part of the "T" straight up, and extend it by a few feet. Leave this leg open to the atmosphere. When running, water will rise up this vertical line a few inches, depending on how much pressure drop is in the line running to your flower pots. When the pump is turned off, this line will drain, and the resulting air intrusion into the line will ensure that the siphon effect is "broken".

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you can also add a vacuum breaker to the top of the piping circuit. this will vent the siphon to atmospheric pressure when the pump shuts off and stop the siphon flow automatically.

Vacuum breakers are commonly used in sprinkler system installations to prevent siphoning and can be bought in hardware stores.

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Install a one way check valve in the vertical line at the exit of the pump discharge. Check valve will open in direction of the water flow due to pump pressure. When the pump is shut off, the valve will close either due to its weight or by a small spring when energy to pump is terminated. A shutoff valve at the crown will make the siphon completely controllable and the siphon will stay primed when the one way check valve at the outlet works effectively.

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  • $\begingroup$ The direction of the water flow does not change when the pump is switched off. What's needed is a "vacuum breaker"---a check valve installed at the highest point in the line. It lets air enter the line when the pump is not running, but it prevents water from escaping when the pump pressurizes the line. $\endgroup$ Jul 20 '16 at 14:01

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