I have been assigned a hands-on project with an adequate budget. The client has given a minimal but adequate description of what they want.

The problem is, it seems impossible, especially at certain (or all) elevations. Even with a perfect pump (but I must use an actual pump from a manufacturer).

I've linked a rudimentary illustration here.

It seems that the necessary Net Positive Suction Head cannot exceed that which is required. Is this the case? (Due to max elevation) If so, I may recommend to the client a re-design - any recommendations?

Please ask if any additional details are needed.

Thank you!


Just mount the pump in the vertical section, either just above the tank or less than 2/3 the way up.

At the height you show the pump will probably not be able to self-prime.

If you can put the outlet on the side or even from the bottom of the tank that would be an advantage.

  • $\begingroup$ Yes, this was my concern. Thanks for the quick response. I'll go ahead and modify it so that the pump is closer to the surface of the water in the reservoir. Can you think of any practical means of conveying 5000 USGPM with a single pump? $\endgroup$ – TinyChickenSandals Apr 28 '19 at 21:58
  • $\begingroup$ You can buy a pump that will do the job off the shelf. But you will need something like a 50kW motor to drive it, and the pump will probably weigh a few tons, so keeping it a ground level would be a good plan. $\endgroup$ – alephzero Apr 28 '19 at 22:24
  • $\begingroup$ Can anyone provide an example of such a device? I know there are limits on motor/pump compatibility, but several man-hours has not yielded a suitable pump/motor combo with 60-100 hp. I'm not sure why I can't find that. $\endgroup$ – TinyChickenSandals Apr 30 '19 at 17:47
  • $\begingroup$ Don't know where you are looking, but Mannesman Rexroth Sigma make some quite good pumps 1 litre per turn and run at 2500rpm (do the cooling for some nuclear plants...) only stand 1 metre high and wide, 60 cm deep, but they weigh a lot... and need a motor about the same size... $\endgroup$ – Solar Mike Apr 30 '19 at 19:59

As mentioned in Solar Mike's answer the lower you have the pump the more efficient operation, and easier priming.

You can even install it submerged under the water, as a sump pump.

As for the second part of your question, Simply no unless you have a huge specially built pump available.

As a very rough estimate one kilowatt rated pump's uotput is 50- 80 Gallons per minutes, depending on the head.

Anything bigger better be 240 or 480 volts and you would need a dedicated electrical panel with an array of the pumps and proper electrical grounding such as red copper stick and bonding.


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