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Minimum Sump Pump Depth

25K views 5 replies 6 participants last post by  Jackofall1 
#1 ·
I moved into an 90 year old house which had an older sump pump so I had it replaced but now it runs every 6 minutes or so and I am concerned it is going to shorten its lifespan fast. Tonight I unplugged sump pump to see how high the water would get and after an hour, it would the water level rest at 12 inches - 3 inches higher than what currently triggers the pump. The well depth to the rocks total 21 inches. Am I okay with raising the pump so water level would rest at 8-9 inches from the top or is that going to present damage to the foundation? Any help would be appreciated.
 
#4 ·
A good rule of thumb is to set the float so the pump turns on when the water level in the sump reaches about four inches below the top of your floor slab. High water table generally does not damage a foundation, as long as you keep the water several inches below the slab, the surface of the slab will remain reasonably dry. Some people like to set the pump to turn on more than four inches below slab elevation, as they believe that maintaining the water table further below the slab elevation reduces the chances of flooding if the pump fails. This is true, but will probably only give you a few minutes of margin, and running the pump too frequently will eventually burn the pump out.
 
#3 ·
I moved into an 90 year old house which had an older sump pump so I had it replaced but now it runs every 6 minutes or so and I am concerned it is going to shorten its lifespan fast. Tonight I unplugged sump pump to see how high the water would get and after an hour, it would the water level rest at 12 inches - 3 inches higher than what currently triggers the pump. The well depth to the rocks total 21 inches. Am I okay with raising the pump so water level would rest at 8-9 inches from the top or is that going to present damage to the foundation? Any help would be appreciated.
Ayuh,... Leave the pump where it is, 'n raise the Switch Point to the level you like...
 
#5 · (Edited)
Generally the sump pump should come on before the perimeter drain pipes entering the pit are significantly submerged. Otherwise water will wait in the drain pipes for a chance to enter the pit and be pumped out and the drain pipes will not do a good job of desaturating the ground all around the house foundation. The basement could even flood at the side or end farthest from the pit while the water level at the pit is below floor level.

My suggestion is to have 20 gallons (about 3 cubic feet) of pit volume below the level of the bottoms of the drain pipes. This gives the pump reasonably long run time on each cycle. This of course would have to be accomplished by either enough width or enough depth of the pit.
 
#6 ·
You will want to set the pump on at a point where the drainage pipe is not flooded and pump off at point when the pump starts to suck air. If it continues to cycle often then there are only a couple of choices, bigger/deeper pit or lower pumping rate (less gpm).

Mark
 
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