You should be able to do a search and find a calculator. It mostly depends on the amount of vertical drop vs the horizontal distance the water travels and the size of the pipe. The "steeper" the pipe is the more differential in pressure is created by the weight of the water.

I do not have a siphon system (bottom draw) and mine is just a surface draw pipe. But it does have several feet drop and when my NRCS guy designed the pond he did calculate its flow when it goes into siphon mode (inlet fully covered and all air expelled from pipe). It would flow lots more than just a horizontal pipe. And if it gets covered with water you can tell it is drawing water and exiting like it was under pressure.

Good luck with the calculations. An on line calculator should be out there. You will need to know the figures to plug in. Pipe diameter, vertical fall and pipe length or horizontal distance.

Last edited by snrub; 10/23/17 08:17 PM.
John

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