Why does a sump pump stop in the middle of a storm?
Most failures come down to three things: the power, the float, or the discharge. A storm stresses all three at once, and a pump that was marginal before the storm often stops during it.
The power is the most common cause, because the storm that brings the water is also the one that cuts the line. A pump without a battery backup stops as soon as the power goes. A float that sticks against the side of the pit, from grit or a broken mount, leaves the pump idle while the water rises. A discharge line that ices up or cracks stops the pump from moving the water it has lifted.
The age of the pump matters too. A pump that has run for many years with a worn switch or a seized impeller can fail without warning, and the first sign is the water on the floor.
What happens to the basement when the sump stops?
The water rises in the pit and then finds the gaps in the slab and the joints along the wall. The floor is the first place it appears, and it can spread under the carpet and the walls before anyone notices.
Water from the ground is under pressure, and it comes up through the slab where the concrete is thinnest or where a crack or a joint lets it through. The water spreads across the lowest part of the floor and runs along the wall. Carpet and pad near the wall take it up quickly, and stored items on the floor are the next to be damaged.
The lower wall is often wet to a height above the floor, and the readings there show how far the water has climbed. The record includes those readings, because the wall is where the drying has to reach.
What does the sump repair involve, and who does it?
The pump, the float, the check valve and the discharge line are repaired or replaced by a plumber or electrician. The restoration work does not repair them, but it records their condition.
A new pump is usually a like-for-like replacement, and the plumber can say whether a battery backup unit suits the house. The check valve is important because it stops the water in the discharge line from running back into the pit. The discharge line should be run well away from the foundation, and its outlet should not freeze in winter.
The owner should ask for the work to be tested with water in the pit before the restoration is closed up, and should keep the plumber's invoice with the restoration file.
How can the next failure be made less likely?
A battery backup, a test before the wet season, a clear discharge line and a float that moves freely are the usual steps. Each one is a plumber's or a homeowner's job, and none of them is a guarantee.
Testing the pump by pouring water into the pit is a simple check that most homeowners can do, and it shows whether the float lifts and the pump discharges. A battery backup should be tested in the same way, and the battery replaced on the manufacturer's schedule.
The discharge line should be checked for a low spot where water can freeze, and the outlet should be kept clear of snow and debris. Those steps cost little and they are the ones most likely to keep a storm from becoming a basement loss.
