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Old 07-05-2008, 12:01 AM   #1
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I'm on a gravity fed water system and I'm trying to tie into my 1 1/4 inch mainline poly pipe to irrigate a garden bed but I have no flow.

My husband and I spliced into the main pipe with a 1 1/4 T adapter and than added an elbow joint, a valve, and reducers that go from 1 1/4 to 1 inch, and than another reducer going from 1 to 3/4. From there we have 3/4 inch poly pipe running to the bed.

I can feel air sucking into the 3/4 pipe and hear gurgling sounds. The pipe runs down slope and away from the main 1 1/4 pipe but instead of flow there is only suction.

Any advice?


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Old 07-05-2008, 05:46 PM   #2
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How high is the supply tank over the elevation of the garden spigot??

BEST cure would be to put a pressure pump on the supply side,where it comes out of tank or supply line. You could buy a good pump for not much money!! Electricity available??

Gravity isnt going to give you too much flow unless tank is like in a skyscraper type storage(then NEXT question is,how did it get UP there??)

Either better give us a better description of what is going on here or pics along with for sure elevations(like transit readings) is this ALL above ground system?? Does it freeze there?? Flow requirements??


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Old 07-05-2008, 06:36 PM   #3
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Is the tank vented?
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Old 07-10-2008, 07:59 AM   #4
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Originally Posted by Gravity View Post

I can feel air sucking into the 3/4 pipe and hear gurgling sounds. The pipe runs down slope and away from the main 1 1/4 pipe but instead of flow there is only suction.

Any advice?
This sounds like you are experiencing aspiration, which is a negative pressure caused by water flowing past an opening. If you have ever seen a waterbed drain kit you've seen an example of aspiration. These kits connect to a faucet, you turn the water on and they suck the water out of the mattress.

In order for aspiration to occur, the water would have to be flowing through you 1 1/4" pipe , so something else would have to be running. or leaking. I would check this first.

I am not really familiar with gravity systems, but basic plumbing principles are just that, principles. If there isn't a means for air to be introduced into the system on the upstream end, the water will not flow properly from the downstream end. If the system is working except for the new line this is probably not the issue, but without more info it's hard to know.

As a rule of thumb, you will have just over 4 psi (4.14) for every 10' the surface of the water in your storage tank is above the point of use.

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