Sump Pump Runs Constantly
Updated February 20, 2026
Runs non-stop or cycles every few minutes? Will burn out prematurely. Stuck float, missing check valve, undersized pump, or high water table. Each has a different fix.
Overview
Designed to cycle: on when water rises, off when it drops. Running constantly or cycling every few minutes means something is wrong. Most common: check valve missing or failed -- water falls back into the pit and the pump repumps the same water endlessly. Second: float switch stuck on or tangled. Continuous running burns out the motor in weeks or months instead of 7-10 years. Fix the cause before you need a new pump.
Symptoms
- Runs continuously even with no rain -- float stuck on or pump cannot lower the level fast enough
- Cycles every 1-3 minutes (short cycling) -- water flowing back into the pit after each cycle. Check valve.
- Runs during dry weather -- water table risen from seasonal changes, nearby construction, or drainage changes
- Hear water flowing back into the pit after shutoff -- check valve missing, stuck open, or failed
- Motor hot to the touch -- continuous running overheats. Cooled by surrounding water, inadequate when level is low.
- Electric bill increased -- pump running 24/7 uses significantly more power
Common Causes
- Missing or failed check valve -- water column in the discharge pipe drains back every time the pump stops. Pump repumps the same water. Number one cause of short cycling.
- Stuck float -- tangled on the discharge pipe, caught on the pit wall, snagged on wires or debris. Constant on signal. Tethered floats are especially prone to tangling.
- Undersized pump -- inflow exceeds capacity at the actual head pressure. Cannot lower the level, never hits the shutoff point. Adequate normally but overwhelmed during high water table events.
- High water table -- continuous seepage, inflow never stops. Not a malfunction, a capacity issue. Larger pump, deeper pit, or address exterior drainage.
- Frozen or blocked discharge -- ice, debris, or crushed section. Pump runs but water has nowhere to go. Recirculates without removing water.
What You'll Need
How to Fix It
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Check the Float Switch
Unplug, remove pit cover. Float tangled on the discharge pipe, caught on the wall, snagged on wires? Free it, confirm full range of motion. Plug back in, pour water to test. Should turn on as water rises, off as it drops. Tether too long? Shorten it.
Tip: Tangles repeatedly? Upgrade to vertical float (rod-guided, cannot tangle) or electronic switch (no moving parts, most reliable). -
Install or Replace the Check Valve
Short cycling? Listen after shutoff. Water flowing back in? Check valve problem. No valve installed? Add one 6-12 inches above the pump outlet. Existing valve stuck or deteriorated? Replace with spring-loaded (quiet) type. Flow arrow pointing up. Should cycle normally after.
Tip: 10-foot discharge, 1.5-inch pipe: about 1 gallon falls back per cycle without a check valve. Thousands of unnecessary cycles. Dramatically shortens pump life. -
Check the Discharge Pipe for Blockages
Trace the entire discharge line to the exit point. Kinks, crushed sections, ice, debris? Exit buried in snow or mud? Frozen? Thaw with warm water or heat gun, never open flame. Recurring freezing? Freeze guard, line heater, or freeze-relief port near the foundation.
Tip: Exit at least 10-20 feet from the foundation, sloping away. Too close? Water seeps back through soil and re-enters the pit. -
Assess Pump Sizing and Capacity
Check valve and float fine but still runs during heavy rain? May be undersized. GPH rating at actual head pressure (vertical distance pumped). 3,000 GPH at 0 feet drops to 1,500 at 10 feet. Inflow exceeds capacity? Upgrade. Most residential: 2,000-3,000 GPH at actual head.
Tip: Estimate inflow: unplug, time the water rise in the pit. Measure pit diameter and inches per minute. Compare volume per hour to pump capacity at your head. Exceeds it? Bigger pump. -
Address Exterior Drainage (Reducing Water Inflow)
High water table? Reduce what reaches the foundation. Downspouts 10+ feet out. Grade soil away (6 inches drop in the first 10 feet). French drains to intercept groundwater. Fix gutters. These exterior improvements dramatically reduce pit volume.
Tip: Downspout extensions: most effective, least expensive. One downspout delivers hundreds of gallons per hour in heavy rain. If it dumps next to the foundation, it goes straight to the pit. -
Install a Battery Backup or Secondary Pump
High water table and concerned about burnout or power outages? Battery backup pump in the same pit. Activates automatically if the primary fails or cannot keep up. Very high inflow? Secondary AC pump set to activate at a higher level. Redundancy and distributed workload.
Tip: Battery backups: 5-10 hours intermittent. Extended outages? Water-powered backup (uses municipal pressure for suction) or generator-powered.
When to Call a Pro
Call a plumber if you cannot find the cause after checking float, valve, and discharge, if you need professional pump sizing, if exterior drainage work is needed, if the pump needs hardwiring or a backup system, or if the pit needs enlarging.
Prevention Tips
- Check valve at installation. Without one, short cycling from day one.
- Pit clean and debris-free. Gravel and objects snag the float.
- Test every 3-4 months: pour water, watch a full cycle, confirm clean shutoff.
- Inspect the discharge exit before winter. Frozen or blocked discharge is the most common cold-weather cause.
- Downspouts 10+ feet out. Proper grading away from the foundation.
- Runs frequently in wet seasons? Plan replacement every 5-7 years, not 7-10.