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Fix a sump pump that runs constantly

We'll check the float, water source, and pump size—then fix the cause or tell you when to call a pro.

Troubleshooting · Home plumbing
15–45 min
What you'll need
  • Bucket or hose (to test water level)
Step 1 of 7

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Steps

Goal: Confirm the symptom, check the float, water source, and pump size—then fix the cause.

  • Look into the sump pit. If the pump runs when the pit is empty or runs continuously without the water level dropping, the pump is running too much.
  • Good: Pump runs when pit is empty or without stopping. Proceed to Check float.
  • Bad: Pump runs only when the pit fills—normal operation.

Check float

Goal: Confirm the float switch shuts off the pump when the water level drops.

  • Locate the float switch. Check that it moves freely and is not tangled, stuck, or resting on the discharge pipe.
  • The pump should shut off when the water level drops and the float lowers. Manually lower the float—the pump should stop.
  • If the float is stuck, free it. If the float cord or rod is too short, adjust the tether or switch height per the manufacturer instructions.
  • Good: Pump stops when you lower the float—float may have been stuck or misadjusted. Bad: Pump keeps running even when you lower the float—proceed to Check water source.

Check water source

Goal: Rule out a continuous water source feeding the pit.

  • If the float works but the pump still runs often, water may be entering the pit continuously. Check for a high water table, surface water draining toward the foundation, or a plumbing leak.
  • Inspect the basement for leaks. Check pipes, the water heater, and the foundation. Fix any leaks you find.
  • Check that gutters and downspouts direct water away from the foundation. Check that the ground slopes away from the house.
  • Good: Fix leaks and improve drainage. Bad: Water table high or inflow constant—proceed to Check pump size.

Check pump size

Goal: Rule out an undersized pump.

  • If water enters faster than the pump can remove it, the pump may run constantly. Check the pump capacity (gallons per hour) and the pit size.
  • A small pump in a high-flow situation will run all the time. Replace with a higher-capacity model if needed. A plumber can help size the pump.
  • Good: Pump can keep the pit level down. Bad: Pump undersized—replace or call a plumber.

When to get help

Call a plumber if:

  • You cannot fix the float or water source.
  • The pump is undersized and you need help sizing a replacement.
  • You are not comfortable with plumbing.

Verification

  • The pump shuts off when the pit is empty or when you lower the float manually.
  • The float moves freely and triggers the pump at the correct water level.
  • No continuous water source feeding the pit, or the pump is sized to handle inflow.

Escalation ladder

Work from the device outward. Stop when the problem is fixed.

  1. Confirm symptom Verify the pump runs when the pit is empty or without stopping.
  2. Float Check that the float moves freely and the pump shuts off when it lowers.
  3. Water source Check for leaks and poor drainage feeding the pit.
  4. Pump size Check if the pump is undersized for the inflow.
  5. Call a pro Call a plumber if you cannot fix the cause or need a larger pump.

What to capture if you need help

Before calling support or posting for help, have these ready. It speeds everything up.

  • Whether the float moves freely
  • Whether the pump shuts off when the float is lowered manually
  • Whether water enters the pit continuously
  • Pump capacity and pit size
  • Steps already tried

Does the pump run when the pit is empty or without stopping?

Look into the pit. If the pump runs when the pit is empty or runs continuously, the pump is running too much.

Look into the sump pit. Good: pump runs when pit is empty or runs without stopping—proceed. Bad: pump runs only when pit fills—normal operation.

Yes No

You can change your answer later.

No action needed

The pump runs only when the pit fills—normal operation. No action needed.

Done

Does the pump stop when you lower the float manually?

Manually lower the float. The pump should stop. If not, the float switch may be faulty.

Lower the float switch manually. Good: pump stops—float may be stuck or misadjusted; free or adjust it. Bad: pump keeps running—switch may be faulty or water is entering continuously.

Yes No

You can change your answer later.

Free or adjust the float

Free the float if stuck. Adjust the tether or switch height per manufacturer instructions. The pump should shut off when the float lowers. If fixed, the issue is resolved.

Done

Is water entering the pit continuously?

Check for leaks, high water table, or poor drainage. Water entering faster than the pump can remove it keeps the pump running.

Check for leaks and drainage feeding the pit. Good: fix leaks and improve drainage. Bad: water table high or inflow constant—check if pump is undersized.

Yes No

You can change your answer later.

Is the pump undersized?

If water enters faster than the pump can remove it, the pump runs constantly. Check pump capacity.

Check pump capacity (gallons per hour) and inflow. If undersized, replace with a higher-capacity pump or call a plumber to size one.

Done

Call a plumber

Call a plumber if you cannot fix the float or water source, if the pump is undersized and you need help sizing a replacement, or if you are not comfortable with plumbing.

Done

Reviewed by Blackbox Atlas

Frequently asked questions

Why would a sump pump run constantly?
A stuck or misadjusted float, a continuous water source (leak, high water table, poor drainage), or an undersized pump that cannot keep up with inflow. Check the float first, then the water source.
How do I check if the float is stuck?
Check that the float moves freely and is not tangled or resting on the discharge pipe. The pump should shut off when the water level drops and the float lowers. Manually lower the float—the pump should stop.
What if water keeps entering the pit?
A high water table, surface water draining toward the foundation, or a plumbing leak can keep the pit filling. Check for leaks and improve drainage. If the water table is high, you may need a larger pump or battery backup.
When should I call a plumber for a sump pump that runs constantly?
If you cannot fix the float or water source, if the pump is undersized, or if you are not comfortable with plumbing. A plumber can size a new pump or address drainage issues.

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