A sump pump only matters when you need it — and that's exactly when failures show up, as a flooded basement or crawlspace. Here are the common causes and how to keep yours reliable.
Written bySteven Lockhart·Reviewed byMiguel Lopez, Owner & Licensed Plumber (CSLB #974600)·Last reviewedJune 2026 · 4 min read
Quick Answer
A sump pump not working usually comes down to a stuck float switch, a clogged pump or intake, a power loss (the most common failure during storms), a worn-out pump, or being overwhelmed by water volume. Because a failure shows up as flooding, the best defenses are maintenance and a battery backup pump that runs when the power is out. This is part of our complete guide to sump pumps in West Los Angeles.
The sump pump failure fix starts with the cause. A stuck or tangled float switch is common — the pump can’t sense the water rising. A clogged intake or debris in the basin stops it pumping. Power loss during a storm disables a standard pump exactly when water is rising. And an old pump simply wears out. Identifying which lets us fix it before the next flood instead of after. This guide is part of our complete resource on sump pumps in West Los Angeles.
A sump pump is a pump set in a basin at the lowest point of a basement or crawlspace that automatically removes collecting groundwater — protecting against flooding when it works and causing it when it fails.
Basement flooding and the sump pump are directly linked — the pump exists to prevent it, so flooding means the pump failed or was overwhelmed. The table maps failure causes to fixes.
| Cause | What happens | Fix |
|---|---|---|
| Stuck float switch | Pump never triggers | Free/replace the switch |
| Clogged intake/basin | Can’t pump water out | Clean; add a basin lid |
| Power loss (storm) | Standard pump dead | Add battery backup |
| Worn-out pump | Fails under load | Replace the pump |
| Overwhelmed by volume | Can’t keep up | Higher-capacity / second pump |
If a sump pump keeps running non-stop, the causes differ from a dead pump: a stuck-on float, a check valve letting pumped water flow back into the basin, a basin that’s too small, or a genuinely high water table feeding it constantly. Each wears the pump out faster, so it’s worth diagnosing. On the prevention side, a sump pump backup — typically a battery-powered backup pump — is the single best upgrade, because it runs during the power outages that knock out standard pumps mid-storm. We diagnose constant-running causes and install backups so a power cut doesn’t become a flood.
A homeowner’s basement floods during a storm when the power goes out and the sump pump dies with it.
New Pro replaces the aged pump and adds a battery backup pump that runs independently of household power.
The next outage doesn’t flood the basement — the backup carries the load until power returns.
The Bottom Line
A sump pump fails right when it’s needed — often from a stuck float, a clog, or a storm power loss — and the result is flooding. Maintenance plus a battery backup are the best protection. We diagnose, repair, and add backups. Call any time. More on our sump pump page.
Common causes are a stuck or tangled float switch (so it never triggers), a clogged intake or basin, a power loss during a storm, a worn-out pump, or being overwhelmed by water volume. We diagnose which and fix it before the next flood.
Most often a power loss — a standard pump runs on household power, which storms knock out exactly when water is rising. That is why a battery backup pump, which runs independently, is the best defense against storm flooding.
Usually a battery-powered backup pump that takes over when the main pump fails or loses power. Since power outages cause many storm-time failures, a backup is the single most valuable upgrade for reliable flood protection.
A stuck-on float, a failed check valve letting water flow back into the basin, a too-small basin, or a high water table feeding it constantly. Continuous running wears the pump out faster, so the cause is worth diagnosing and correcting.
Maintain the pump (test it, keep the basin and intake clear, check the float and check valve) and add a battery backup so a power loss doesn’t leave you unprotected. For high-volume situations, a higher-capacity or second pump helps.
Periodically, and especially before the rainy season — pour water into the basin to confirm it triggers and pumps out. We can service it, verify the float and check valve, and recommend a backup if you don’t have one.
Written by the New Pro Plumbing content team and reviewed for technical accuracy by Miguel Lopez, owner and California-licensed plumber (CSLB #974600). Pipe lifespans are presented as typical ranges, not guarantees, and any pricing is confirmed in writing before work begins.
What's new: June 2026 — first publication.
We diagnose, repair, and add battery backup so the next storm doesn't flood you — flat-rate. Call any time.
