What a proper pit looks like
A perforated liner, about 45–60 cm across and 60–75 cm deep, set in clear stone below the slab so water enters from all sides and from the weeping tile. The pump stands on a solid base — a paver, not the bottom of the liner — so it does not draw silt. A check valve on the riser stops the column of water in the discharge line falling back into the pit every cycle. A sealed lid keeps radon, moisture and smell out of the room and small hands out of the pit. The discharge line leaves the house and ends on ground that falls away.
Why pumps fail
- Power. The storm that fills the pit is the storm that takes the hydro. A pump without backup is a pump that stops when it is needed most.
- The float. A tethered float jammed against the liner wall never switches on. A vertical float in a clean pit does.
- The discharge. A line that ends at the wall sends the water back to the pit; a line that holds water freezes in January and the pump runs against a plug of ice.
- Age. A submersible pump that cycles often in this water table lasts seven to ten years. Nobody replaces one until it stops.
Backup options
A battery backup is a second pump on a deep-cycle battery with its own float set above the main one — it runs for several hours of steady inflow and sounds an alarm when it starts. A water-powered backup uses municipal water pressure to draw water from the pit with no electricity at all; it runs as long as the town supply does, but it needs municipal water, so a house on a well takes the battery. Both are installed in the same pit as the main pump.
Groundwater through the floor
Water rising through a crack in the slab or at the middle of the floor is not a wall problem; it is the water table above the slab. The fix is a pit and pump, usually with an interior drain around the perimeter feeding it so water is collected at the footing before it reaches the floor.