Why Sump Pumps Fail at the Worst Possible Time
There's a pattern to sump pump failures: they rarely happen on dry, calm days. They happen during the storms that send an inch of rain in an hour, when the ground is already saturated and water is pushing hard against your foundation. By the time you realize the pump isn't working, water is already coming into the basement. Understanding why sump pumps fail — and when — can help you avoid that scenario.
The Most Common Reason: Power Outage
The irony of sump pump design is that the conditions most likely to cause a power outage are also the conditions when a sump pump is most needed. A severe thunderstorm knocks out power, the sump pump goes offline, and water flows into the basement unimpeded. This is why battery backup sump pumps exist and why they're worth the investment for any home with a finished basement or valuable stored belongings.
The Red Cross flood preparation guidance specifically recommends having a backup pump system and keeping it tested and ready.
Motor Burnout From Continuous Running
During heavy, sustained rainfall, a sump pump may run nearly continuously — far more than it's designed to handle in a short period. If the pump motor overheats, it shuts off (or burns out entirely) right when you need it most. Proper sizing is part of the answer here — a pump that's appropriately sized for your pit volume and typical inflow rate won't have to work at the edge of its capacity during heavy rain.
Float Switch Problems
The float switch is the sensor that tells the pump to turn on when water rises in the pit. If the float gets stuck in the down position, the pump never activates even as water rises. If it gets stuck in the up position, the pump runs continuously until it burns out. Checking that the float moves freely during routine testing is an important but often overlooked step.
Age and Lack of Maintenance
A sump pump that hasn't been tested in years may technically be sitting in the pit, but there's no way to know if it will work when you need it. Testing twice a year — pour a bucket of water into the pit and confirm the pump activates and discharges — takes five minutes and confirms the pump is operational. An aging pump in the 8-10 year range should be evaluated for replacement before it fails during a storm.
Check Your Discharge Line
Even a functioning pump can't help if the discharge line is blocked or frozen. The line should direct water well away from your foundation — if it discharges too close to the house, that water can find its way back into the ground around the foundation and right back into your basement.
Our technicians do not work on commission. If your sump pump is aging, has never been tested, or if you've had any basement water intrusion, our team can help. We provide plumbing service in St. Charles and throughout the region. Our residential plumbing services cover all of St. Charles, St. Louis, Lincoln and Warren Counties.
Call (636) 397-3200 to schedule a sump pump inspection or replacement, or request service online at aaastl.com. Don't wait for the next big storm to find out whether your pump is up to the job.
