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A well...

CREZIERES, France(Zone 8a)

I have a well - it is 20 meters deep and the last 5 meters are full of water...
A few years ago I tried to buy a pump to allow me to use the well water for irrigation... it was a magnetic submersible electric pump of Russian construction.
I allowed my neighbour to use it and he left it on overnight, the well water dried up and the pump ceased to function. I sent it back to the seller (I am in France) and he agreed to repair it... but it only worked for a few hours then stopped. The seller said that one cannot use the pump to provide continuous pressure for a sprinkler or the like... only to allow the water to gush out wherever the end of the hose happens to be.

So... my question is... does there exist a type of pump that can raise water 15 - 20 meters and provide continuous water pressure? (Since I am in France, I want the type of pump, not the brand/manufacturer).


Everett, WA(Zone 8a)

I looked at the "pump" section of a wholesaler's catalog I have.

One said "designed for "continuous duty". None said "intermittent use only" or cited a safe duty cycle (% on time).

A few had "thermal protection", which sounds good if it might overheat.

Several had a "7 foot shut-off head capacity". I GUESS that means that, when the back-pressure is equivalent to a 7-foot-tall column of water, it shuts down. That's just a guess. But 7 feet of water is 16 psi (110 kPa?), so there would have to be some very wimpy pumps out there!

Maybe that's what Ivan meant by "allow the water to gush out". Very low back pressure.

Now here are some suggestions based on no knowledge or experience whatsoever! Don't take my word for anything, or spend money based on these ideas. But perhaps this will suggest some good questions for you to ask of someone who is better-informed than I am.

15-20 meters uphill sounds like 50-66 feet of water head. Or 22-29 psi at the submerged pump, just to get water pushed up to ground level . (175 kPa?) That's a lot of work right there. If you just 'let it gush out' right there, how fast does it come out?

Call that 25 psi, and I assume that your irrigation setup needs 20 psi to function (a fairly low-pressure system).
That's a total required back-pressure of 45 psi (310 kPa).

So the pump has to be able to labor against that without overheating or giving up.

And it has to deliver _enough flow rate_ , at that back-pressure, to maintain that much pressure despite some number of liters per hour coming out of your emitters.

You might double or triple the number and size of your drip emitters or sprayers, so they will emit enough water, even with less back pressure.

I would ask a salseman for a pump that can throw X liters per hour aginst a back-pressure of 300+ kPa without overheating.

If that is too expensive, consider two pumps: one to get the water out of the well and into a holding tank or barrel. That has to push 30 psi (210 kPa) at some flow rate, perhaps a low rate. Maybe a float valve in the barrel to shut the pump off.

And buy a second pump to go from that barrel into your irrigation setup. That has to deliver enough flow and pressure to operate your emitters or sprayers reliably and uniformly.

If the barrel is big enough, for example a discarded water heater shell or pond, you might get by with just one pump that can handle 30 psi back-pressure. Pump from the well up to the pond for a few hours, and then just move the pump up to gorund level and now push the pond water through your tubing.

Maybe buy a timer in addition to a thermally-protected pump. Only run the pump for 10 minutes at a time, and leave it off for 20 minutes. But use a check valve, or the pump will spend all its energy re-filling the tubing after it all drains back inot the well.

These are all just guesses. I don't know if they are practical.

6.9 kPa per PSI
2.3 feet of water per PSI
3.3 feet / meter
3.8 liters per gallon

This message was edited Mar 29, 2013 1:45 PM

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