How deep can a pump "suck" water from?

Users who are viewing this thread

Status
Not open for further replies.

gsecord

New Member
Messages
14
Reaction score
0
Points
0
Location
Michigan
can somebody explain why a shallow well pump wont suck water at a depth of 29 ft? what kind of pump will and do you have any suggestions
thanks
george
 

Bob NH

In the Trades
Messages
3,310
Reaction score
9
Points
0
Location
New Hampshire
A shallow well pump won't suck water from 29 ft because it is at or beyond the limit of the physics and mechanics of the system.

"Sucking" water doesn't actually describe how it works. A shallow well pump removes air from the suction line and allows atmospheric pressure to push the water up. Because atmospheric pressure is limited (about 14.7 psi at sea level, but only about 14.2 psi in Michigan) that is the limit to which it can push the water. A pump can't produce a perfect vacuum because the water evaporates at perfect vacuum, but the real limit is a characteristic of the pump that requires a minimum Net Positive Suction Head, often abbreviated NPSH Required. It requires that minimum pressure (NPSH) to avoid cavitation at the inlet of the pump.

Because of those factors, the limit for reliable operation of a shallow well pump is usually given as 25 ft of lift from top of water in the well to the inlet elevation of the pump. That is further diminished if the line from well to pump is too small or too long so that it causes additional pressure loss in the pipe.

The alternative is to use a deep well jet pump that involves putting a venturi/ejector in the bottom of the well with a supply pipe and a lift pipe; or make the well big enough to install a submersible pump, which is usually a 4" minimum diameter well. Deep well jet pumps are so inefficient that most new deep wells are drilled large enough for a submersible pump.
 
Last edited:

gsecord

New Member
Messages
14
Reaction score
0
Points
0
Location
Michigan
shallow well

ok bob thanks for the information it was very helpful talk at you later
george
 

hj

Master Plumber
Messages
33,599
Reaction score
1,037
Points
113
Location
Cave Creek, Arizona
Website
www.terrylove.com
suck

A contractor came into our store once. He was building a concrete "slip form" building in Texas and wanted a pump to suck water to keep it lubricated as it was moved upwards. He wanted the tank to be on the ground and the pump to be on the successive floors as they were finished. I told him, "You can pump the water all the way to the Moon, but you can only "suck" it 25 feet". 15 psi air pressure at the Earth's surface it the limiting factor. The higher your elevation, the shallower the well has to be.
 

pudge565

New Member
Messages
23
Reaction score
0
Points
0
For every foot that you pull the water you will lose .5 psi. so at normal atmospheric pressure you should be able to raise the water about 28-29 feet. just learned this through a pump class for firefighting.
 
Status
Not open for further replies.
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks