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I have a 200 litre water tank on my balcony with a submersible pump at the bottom and a hose + drip system attached.

Pump is supposed to automatically switch on twice a day while we're on vacation.

During the first week of testing, the tank was running almost empty already while I calculated 200 litres to be sufficient for about 2 weeks.

The problem is, that the water which remains in the hose creates underinflation which sucks the tank empty even with inactive pump. Water continues to flow till the water level in the tank reaches the height of the sprinkler outlets attached to the end of the hose.

Do you have any suggestion how to avoid ongoing waterflow with disabled pump? I can't really move the plants to a higher location so the water level in the full tank will always be above the level of the output sprinklers.

This is the pump I am using https://www.amazon.de/dp/B00B18KADW/

sketch of the setup

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2 Answers 2

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If I'm understanding what you're saying correctly, it sounds like you need to install what's called a spring check, a little device that only opens when there's a certain about of pressure applied to the upstream side. The ones I've shown can be adjusted. I would install it at one of two locations (the decision is up to you):

  1. after the top of the tank, but about equal to the height if the first emitter / head,
  2. at the lowest point prior between the top of the tank and the first branch in your distribution piping.

It doesn't really matter, the idea is that all the water upstream of that point will be trapped. I would base it on layout and where I'd trap the most water.

A word of caution though, there's a very similar device called a swing check, which you don't want - it keeps water from going back up the pipe at low pressures.

Another (additional) thing that you can do to prevent excess water from leaking out is to always (or as often as is practical) keep the emitters / heads above the distribution piping.

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  • That's exactly what I was looking for. Thanks so much!
    – Michel Feldheim
    Jul 17, 2017 at 17:20
  • Btw the spring check worked well. Later I also had to replace the submersible pump with a pressure pump to keep the pressure high enough for all my sprinkler outlets (60+). The way a submersible low pressure pump is built allows water flow through it when shut down
    – Michel Feldheim
    Feb 16, 2018 at 12:42
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A typical solution is to put a "vacuum breaker" in line (say as the pipe goes out the top of the tank) - this permits flow under pressure, but when suction comes into to play it vents the pipe to air, breaking the siphon. It does not cause any restriction in the pumped flow.

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  • Would probably even be the cheaper solution compared to a spring check - and frost safe
    – Michel Feldheim
    Jul 19, 2017 at 8:20

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