Most sump pumps in the Lower Mainland do almost nothing from May to September. Then the first big storm of the season arrives, the water table comes up, and a pump that hasn't run in months is suddenly expected to keep up with hours of steady inflow. That is when we hear about pumps that hum but don't move any water, pumps that never start, and pumps that won't stop.
This guide covers what to do if water is rising right now, how to work out why the pump quit, and the short check that catches most of these failures before the rain does.
If the water is rising right now
- Stay out of standing water if it is anywhere near outlets, extension cords or the electrical panel. Water and electricity together is the real danger here, not the mess.
- Check that the pump has power: the plug, the outlet and the breaker. Many basement pumps are plugged into a GFCI outlet, which can trip on its own, so press its reset button.
- Look at the float. If it is jammed against the side of the pit or caught on the cord, freeing it with a broom handle is often enough to start the pump.
- If the pump hums but no water moves, unplug it. A pump running against a blocked line or a jammed impeller can burn out its motor.
- Move what you can off the floor and call for help. A wet/dry vac or a bucket can buy you time, but neither will outrun a steady inflow.
Why sump pumps stop working
Nearly every failure we see comes down to a handful of causes, and most of them have nothing to do with the motor.
- Power: a tripped GFCI or breaker, a loose plug, or a power cut during the storm itself.
- A stuck float switch. The float has to rise freely to turn the pump on, and debris, a pump that has shifted in the pit, or a cord that has drifted into its path will hold it down.
- A failed check valve. This one-way valve on the discharge pipe stops pumped water falling back into the pit. When it fails, the pump empties the pit and the same water runs straight back in.
- A blocked or disconnected discharge line: leaves over the outlet, a crushed pipe in the garden, or a joint that has come apart.
- A clogged intake or impeller, usually gravel, silt and debris drawn up from the bottom of the pit.
- An undersized pump. It runs flat out in a heavy storm and still loses ground, because more water is coming in than it can move.
- Age. Motors and switches wear out, and a pump that has worked hard for years may be due regardless of what failed this time.
What the sump pump alarm is telling you
A high-water alarm sounds when the water in the pit climbs above the point where the pump should already have switched on. It can't tell you why. It only tells you the pump is either not running or not keeping up. Treat it as an early warning, because there is usually a short window before water reaches the basement floor.
On a battery backup system, the alarm can mean something else: the backup pump has taken over because the main pump failed or the power went out, or the battery itself needs attention. Check the label on your backup unit, since alarm patterns vary from one model to the next.
Running nonstop, or switching on every few minutes
A pump that runs constantly through a downpour may simply be doing its job against a high water table. A pump that starts and stops every few minutes in light weather usually points to something else.
- A check valve letting water flow back into the pit
- A float set so low that the pump switches on for very small amounts of water
- Discharge water landing too close to the house, so it soaks back to the foundation and the perimeter drain collects it again
- A pit too small for the pump, so it refills almost as soon as it empties
Short cycling wears a pump out much faster than steady running. If yours never seems to rest, get it looked at before the wettest months arrive.
Where the water goes matters
The discharge has to carry water well away from the foundation, or the pump ends up pumping the same water over and over. It also has to end up somewhere your municipality allows. Rules differ from city to city, and most do not allow groundwater to be sent into the sanitary sewer, so check with your municipality before you re-route a discharge line or connect it to anything new.
When the problem is upstream of the pump
Sometimes the pump is fine and the water isn't reaching it, or it arrives full of silt. Perimeter drains around older homes can clog with roots and sediment, so water builds up against the foundation instead of flowing to the sump. If the basement walls get damp while the pit stays low, that is worth investigating. A drain camera inspection can show whether the drain is blocked or broken.
A ten-minute check worth doing every October
- Pour water slowly into the pit until the float rises, and confirm the pump starts and empties the pit cleanly
- Listen as it shuts off. A single clunk from the check valve closing is normal; water you can hear running back into the pit is not.
- Go outside to the discharge outlet and clear away leaves, soil or anything growing over it
- Lift debris out of the pit and make sure the float moves freely
- Test the high-water alarm if you have one
- If you have a battery backup, test it with the main pump unplugged and check how old the battery is
Our annual plumbing maintenance checklist covers the rest of the house the same way.
Repair or replace?
A float, switch or check valve can be replaced on its own, and on a newer pump that is often the right call. On an older pump that has already struggled through a storm season, replacing the whole unit usually makes more sense than repairing it twice.
If you are choosing a new pump, our sump pump buying guide explains the main pump types, how sizing works and when a battery backup is worth adding. For repairs and replacements, see our sump pump service page, and if water is already coming in, our emergency plumbing line is answered 24/7.
Dealing with this right now? Mr. Plunger Plumbing & Drainage answers 24/7 across Surrey, Delta, Langley, White Rock, Richmond, Maple Ridge, Pitt Meadows, Vancouver and the rest of the Lower Mainland. Call (604) 870-1442 to talk to a real plumber, get an ETA before anyone is dispatched, and get a quote before any work starts.