On 04/08/2019 20:04, Tim+ wrote:
Why not syphons? I mean, pumps use power, quite a lot of it and are
relatively expensive. For a syphon, you just need a suitably sized bit of
pipe.

Tim


You've already said it: suitably sized.

I don't know how far they need to deliver the water, but the flow rate
is dependent on the frictional losses. The pumped system still recovers
available potential energy. To get the same flow rate from a syphon will
require *much* larger hoses, especially if they are long.