A sump pump that has stopped working is an emergency in March and an inconvenience in July, and in both cases the first instinct is to buy a new one. Roughly half the time that is the wrong purchase.
Six things fail, and only two of them are the pump.
1. The float switch
The most common failure by a wide margin, and it fails in two directions.
Stuck down, and the pump never starts — the pit fills and eventually goes over the top of the liner. Stuck up, and the pump runs continuously against no water, which burns it out in a day or two.
Floats stick for dull reasons. A tethered float swings against the side of a pit that is too narrow. A vertical float binds on its rod after years of silt. The pump has shifted on the pit floor and the float is now touching the wall, or the discharge pipe, or the power cord.
Test it: unplug the pump, lift the float by hand, plug it back in. If it starts, the pump is fine and the switch or its clearance is the problem.
2. The check valve
The valve on the discharge pipe just above the pump, which stops the column of water in that pipe falling back down when the pump shuts off.
When it fails, the pump empties the pit, shuts off, and the water in the vertical pipe drops straight back in. The pit refills, the pump restarts. The symptom is a pump that cycles every thirty to sixty seconds and never seems to get ahead, and it is regularly misdiagnosed as “the water table is high” and answered with a bigger pump.
Test it: listen after the pump shuts off. A distinct rush of water back into the pit is a failed valve. It is an inexpensive part.
3. The discharge line, outside
How does a sump pump work? Water has to actually go somewhere, and in this climate the outside end of that pipe is a seasonal liability.
In winter the discharge line freezes. A pump that is working perfectly, pushing into a plugged pipe, will run until it overheats — we cover the whole failure in the frozen sump discharge line. In summer the same pipe gets crushed by a vehicle, blocked by a mouse nest, or buried under mulch by a landscaper who did not know what it was.
Test it: run the pump and go outside. If nothing comes out of the end of the pipe, the pump is not your problem.
Two further points about that pipe:
- It must not discharge into the sanitary sewer. That is prohibited, and it is part of why sewers surcharge and back up into basements on the same street during a storm.
- It must clear the backfill trench. A discharge ending a metre from the wall is pumping the same water back into the loose soil around your foundation, where it returns to the footing and the pit. We have seen pits cycling all summer for no other reason.
4. Power
Obvious, and it is still the answer often enough to check it second.
A tripped breaker, a receptacle that has quietly died, or a pump that was unplugged so somebody could run a shop vacuum during a basement project and never plugged back in. Also worth knowing: a pump plugged into an extension cord shares a fate with whatever else is on it.
The version that matters here: the March thaw and the storms that bring down power in Simcoe County arrive in the same weeks. A pump with no backup is a pump that stops at exactly the moment the pit is filling fastest. A battery backup at $700–$1,400 is the cheapest insurance in a basement, and a backup with a battery nobody has tested since it was installed is not a backup.
5. Debris in the impeller
The pump hums, draws power, and moves nothing.
Pits without a proper stone bed and liner throw grit. Gravel, sand and bits of concrete find the impeller and jam it. So do the things that end up in an open pit in a working basement — screws, plastic, insulation.
Unplug it first. Then lift the pump out and look at the intake. Some clear in five minutes with the power off and a screwdriver. A pump that has been running jammed has usually cooked its motor, and that one is a replacement.
6. The pump is simply finished
Eight to ten years is a fair working life. Pumps here get an unusually hard duty cycle because the snow-belt thaw loads them for weeks at a stretch rather than for the hours a rainstorm demands, so a fifteen-year-old pump in a Barrie basement has done more work than its age suggests.
Signs it is at the end: rust at the housing seams, a noticeably louder or rougher note than it used to make, longer run times to clear the same pit, and a motor casing hot to the touch after a normal cycle.
| Job | Typical Barrie cost |
|---|---|
| Replace the pump in an existing pit | $550–$950 |
| New pit, liner, stone bed, sealed lid, pump | $1,200–$2,000 |
| Add a battery backup pump | $700–$1,400 |
When the pump is not the problem at all
Three situations where a new pump changes nothing.
The pit never fills, and the basement is still wet. Water is arriving somewhere the pit cannot reach it — a crack, a window well, a grade problem, surface water at the top of the wall. Start with where the water actually enters instead.
Water is coming up out of the floor drain. That is the sanitary sewer, not groundwater, and no pump in your pit addresses it. A backwater valve does.
The pit fills faster than any pump can clear it, every spring. That is not a pump problem, it is a drainage problem — usually original clay weeping tile that has silted or collapsed. Fitting a larger pump manages the symptom for another year while the actual system stays failed.
The one thing to do in February
Pour a bucket of water into the pit and watch what happens. The whole test takes two minutes.
Does the float rise and the pump start. Does the pit clear. Does water come out of the far end of the discharge pipe. Does the pump stop cleanly without immediately restarting. If the answer to all four is yes, you are ready for the thaw. If it is no to any of them, you have found it in February at a normal price rather than in March at an emergency one.