Plumbing Resource

Repairing a Sump Pump

Repairing a Sump Pump: A Step-by-Step Guide

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by

Gilbert Olivarez
in , ,

When a sump pump fails, it usually fails at the worst possible moment-during heavy rain, rising groundwater, or a plumbing leak. However, with a careful approach and step-by-step troubleshooting, you can often repair a sump pump yourself and restore protection to your basement or crawl space.

In this guide, you will learn how a sump pump works, how to diagnose common problems, and how to repair issues ranging from simple clogs to electrical faults and float failures.

1. Safety First: Before You Touch the Pump

Because sump pumps sit in pits with water, electrical safety is critical.

Step 1: Assess the situation visually

  • Look at the pit first, without touching anything.
  • If water is covering the outlet, the plug, or any electrical connection:
    • Do not touch the pump or outlet.
    • Turn off power to that circuit at the breaker panel.
    • Consider calling a licensed electrician or plumber for safety.

Step 2: Shut off power to the pump

  • Unplug the sump pump from the GFCI outlet before you reach into the pit.
  • If the pump is hard-wired (less common in residential settings):
    • Turn off the appropriate breaker at the electrical panel.
    • Verify the pump is off by gently lifting the float-there should be no sound or vibration.

Step 3: Wear proper protective gear

To stay safe and sanitary, wear:

2. Understand the Main Parts of a Sump Pump System

Before repairing, it helps to know what you are looking at.

Most basic systems include:

  1. Sump pit (basin)
    A hole in the floor that collects water. Can be plastic or concrete.
  2. Sump pump (submersible or pedestal)
    • Submersible: sits down in the pit, fully submerged.
    • Pedestal: motor sits above the pit, with a pipe down into the water.
  3. Float switch
    A mechanism that turns the pump on and off as water rises and falls.
    • Can be an integrated vertical float, tethered float, or an external switch.
  4. Discharge pipe
    A PVC or similar pipe that carries water out of the house and away from the foundation.
  5. Check valve
    A one-way valve on the discharge line that prevents pumped water from flowing back into the pit.
  6. Power source and outlet (often GFCI)
    Provides electricity to the pump. A tripped GFCI is a very common problem.

Understanding these parts will make each repair step much clearer.

3. Tools and Materials You May Need

You might not need everything on this list, but it helps to be prepared:

4. Diagnose the Problem: Symptom-Based Troubleshooting

Instead of randomly swapping parts, start by identifying what the pump is doing (or not doing). Here are the most common symptoms and what they usually indicate.

Symptom A: Pump Will Not Turn On at All

Possible causes:

  • No power (tripped breaker or GFCI)
  • Bad outlet
  • Faulty float switch
  • Burned-out motor

Symptom B: Pump Hums but Does Not Pump Water

Possible causes:

  • Impeller clogged or jammed
  • Discharge line clogged or frozen
  • Check valve stuck closed
  • Motor failing

Symptom C: Pump Runs but Water Level Does Not Go Down

Possible causes:

  • Discharge pipe blocked or frozen
  • Check valve installed backward or stuck
  • Broken impeller
  • Pump undersized for volume coming in

Symptom D: Pump Runs Constantly or Cycles On and Off Rapidly

Possible causes:

  • Stuck float switch
  • Float hitting side of pit or discharge pipe and not dropping
  • Water recirculating back into pit (bad or missing check valve)
  • High water infiltration rate (pump undersized or high water table)

Symptom E: Breaker or GFCI Keeps Tripping

Possible causes:

  • Moisture in outlet or plug
  • Short in pump motor or cord
  • Overheating motor drawing too many amps
  • Wrong size breaker/wiring issue (call an electrician if suspected)

5. Step-by-Step Repair Process

We’ll walk through a logical order of operations that covers nearly all scenarios.

5.1 Step 1 – Verify Power Supply

  1. Check the outlet:
    • Plug a lamp or phone charger into the same outlet.
    • If it does not work:
      • Press the reset button on the GFCI outlet (if present).
      • If it still does not work, check the breaker.
  2. Check the breaker:
    • Go to the electrical panel.
    • Look for any tripped breakers (often slightly off center).
    • Reset any tripped breaker once.
    • If it immediately trips again when the pump tries to run, stop and move to troubleshooting the pump itself. There could be an electrical fault.
  3. Test the pump in a different outlet:
    • If possible, plug the pump into another GFCI outlet on a different circuit (using an extension cord rated for the load).
    • If it runs properly there, your first outlet/circuit may be the problem.

If power issues persist after this step:
You may need an electrician, especially if multiple outlets or breakers are acting up. Do not repeatedly reset a breaker that keeps tripping.

5.2 Step 2 – Test the Float Switch

The float is one of the most common failure points, and many “dead” pumps are simply suffering from a stuck or broken float.

  1. Visually inspect the float:
    • Is it caught under the discharge pipe, against the pit wall, or under debris?
    • If it’s tethered, is the tether too tight or wrapped around the pump?
  2. Manually lift the float:
    • With the pump plugged into a working outlet, slowly lift the float.
    • You should hear the pump motor start when the float reaches a certain height.
    • If nothing happens:
      • Plug the pump directly into the outlet (some pumps have separate float plugs-one for the float, one for the motor).
      • If bypassing the float makes the pump run, the float switch is bad.
  3. Free a stuck float:
    • Reposition the pump so the float can move freely up and down.
    • Use zip ties to secure the float cord so it cannot get entangled.
    • If the float is waterlogged (full of water) or cracked, replace it.
  4. Replace a failed float switch (basic overview):
    • Unplug the pump.
    • On pumps with external float kits:
      • Remove the old float assembly from the discharge pipe or pump body.
      • Install the new float according to manufacturer instructions.
      • Adjust the height so that the pump turns on when the water level nears the top of the pit but well before overflowing.
    • On pumps with integrated float switches:
      • Sometimes the entire pump must be replaced if the float is non-serviceable.

Important: If the float is hard-wired into the pump housing, and you are not experienced with electrical repairs, it is safer to replace the pump or call a professional.

5.3 Step 3 – Check the Discharge Line and Check Valve

If the pump runs but doesn’t move water effectively, your issue might be downstream.

  1. Locate the check valve:
    • Usually installed on the vertical discharge pipe just above the pump or a few feet higher.
    • Often labeled with an arrow showing the flow direction.
  2. Verify orientation:
    • The arrow on the valve should point upward, away from the pump and toward the discharge termination.
    • If it is installed upside-down, water will not leave the pit properly.
  3. Test the check valve:
    • With power off and pump unplugged, loosen the clamps or unions on the check valve.
    • Carefully remove it (have a bucket ready; water may drain out).
    • Check inside for debris, stuck flapper, or broken pieces.
    • Clean it and test it by gently blowing air or water through from the pump side. It should allow one-way flow only.
  4. Inspect the discharge pipe:
    • Look for:
      • Sagging sections that may hold water and freeze.
      • Visible cracks or leaks.
      • Obstructions at the outlet where the pipe discharges outside (leaves, mud, ice, or pests).
  5. Address common discharge pipe issues:
    • Clogged outlet: Clear debris with a rod or garden hose.
    • Frozen line: Carefully thaw the line using warm towels or a safe heat source outside the home. Do not use an open flame.
    • Leaking sections: Replace cracked or broken sections with new PVC, using proper primer and cement.
  6. Reinstall or replace the check valve:
    • If the valve is damaged, install a new one.
    • Ensure all clamps or unions are tight and properly sealed.

5.4 Step 4 – Remove and Inspect the Pump

If power, float, and discharge line all check out, it’s time to pull the pump from the pit.

  1. Prepare the work area:
    • Lay down a tarp or cardboard next to the pit.
    • Have a bucket or pan ready to catch water.
  2. Disconnect the pump:
    • Unplug the power.
    • Loosen the clamp or union at the base of the discharge pipe.
    • Carefully lift the pump out by the handle or discharge pipe (not by the cord).
  3. Inspect the pump body:
    • Look for cracks, rusted areas, or obvious damage.
    • Check that the pump housing is not packed with sludge or gravel.
  4. Check the impeller:
    • On most pumps, the impeller is accessible from the bottom or side by removing a few screws.
    • Remove the cover plate to expose the impeller.
    • Look for:
      • Gravel, debris, or string wrapped around the impeller.
      • Broken fins.
    • Clean everything thoroughly with water and a brush.
    • Spin the impeller by hand; it should move freely.
  5. Reassemble the pump:
    • Reinstall any covers or screws securely.
    • Ensure the gasket or O-ring (if present) is seated correctly.
  6. Optional: Bench test the pump outside the pit:
    • Place the pump in a large bucket or tub of water.
    • Plug it in and lift the float if needed.
    • Confirm that water is pumped out strongly through the discharge connection.

If the pump hums, overheats quickly, or fails to spin the impeller even after cleaning, the motor may be failing and replacement is often more cost-effective than repair.

5.5 Step 5 – Clean the Sump Pit

A clogged, sludge-filled pit can shorten pump life and cause ongoing problems.

  1. Remove debris:
    • Scoop out rocks, gravel, and large debris by hand (with gloves).
    • Use a bucket to remove excess water if needed.
  2. Vacuum sludge:
    • Use a wet/dry shop vac to suck up fine sediment and muck from the bottom.
  3. Inspect the bottom of the pit:
    • Make sure the pump will sit on a relatively flat, stable surface.
    • Consider placing the pump on a small concrete paver or plastic pump stand to keep it slightly off the very bottom and away from heavy sediment.

5.6 Step 6 – Reinstall the Pump and Adjust the Float

  1. Place the pump back into the pit:
    • Lower it carefully onto the bottom or pump stand.
    • Ensure it is level and stable.
  2. Reconnect the discharge pipe:
    • Reattach the pipe to the pump outlet or check valve.
    • Tighten all clamps or unions securely.
  3. Reposition and secure the float:
    • Make sure the float has a clear vertical path with no obstructions.
    • Use zip ties to secure any cables to the discharge pipe so they do not interfere with the float movement.
  4. Plug in the pump:
    • Use a GFCI-protected outlet.
    • If the pump and float have separate plugs, plug them in according to manufacturer instructions (often float into outlet, pump into float).

6. Test the System Thoroughly

Never walk away without a full test. You want to see the pump work from start to finish.

  1. Fill the pit with water:
    • Use a bucket or hose (if allowed) to slowly fill the sump pit.
    • Watch as the water level rises and the float gradually lifts.
  2. Observe pump activation:
    • Note the water level when the pump turns on.
    • The pump should start before water gets close to the top of the pit.
  3. Watch the discharge:
    • Go outside and confirm water is flowing strongly at the discharge point.
    • Check for leaks in the piping and around the check valve.
  4. Confirm shut-off level:
    • After pumping down, the float should drop and turn the pump off.
    • The pump should not continue running once the water level is low.
  5. Check for short cycling:
    • If the pump turns on and off very frequently with small water level changes:
      • Adjust the float height or tether length so the pump runs less often but longer per cycle.
      • Verify the check valve is functioning and not allowing water to flow back into the pit.

7. When to Replace the Pump Instead of Repairing It

Even with the best repairs, sometimes replacement is the smarter choice. Consider replacing the pump if:

  • The pump is over 7-10 years old and failing repeatedly.
  • The motor hums but will not turn the impeller, even after cleaning.
  • The pump trips breakers or GFCIs due to suspected internal electrical faults.
  • The pump housing is cracked or severely corroded.
  • Replacement parts (like integrated floats) are not available or cost almost as much as a new pump.

A new, properly sized, and correctly installed sump pump can provide peace of mind for many years.

8. Preventive Maintenance Tips to Avoid Future Repairs

Once your sump pump is up and running again, you should keep it that way with regular maintenance.

  1. Test the pump monthly (or at least quarterly):
    • Pour water into the pit until the pump cycles on.
    • Confirm proper start, pumping, and shut-off.
  2. Clean the pit at least once a year:
    • Remove debris, sludge, and sediment.
    • Verify the pump is sitting flat and the float moves freely.
  3. Inspect the discharge line before winter:
    • Ensure it is not sagging or blocked.
    • Confirm that the outlet is clear of dirt, mulch, and ice.
  4. Replace the check valve when needed:
    • If you hear loud banging (water hammer) or notice water rushing back into the pit after the pump shuts off, consider a new check valve.
  5. Consider a backup system:
    • Battery backup sump pumps or water-powered backup pumps can protect your home if the main pump fails or the power goes out.

9. Final Thoughts

Repairing a sump pump can seem intimidating at first, because it involves both water and electricity. However, when you take your time, follow safety precautions, and work through the problem step by step, most common issues are fixable by a careful homeowner.

By understanding how your sump pump works, recognizing the symptoms of trouble, and performing regular maintenance, you can dramatically reduce your risk of a flooded basement and the costly damage that comes with it.

If at any point you feel unsure-especially with electrical issues or repeated breaker trips-do not hesitate to call a licensed plumber or electrician. Your safety and your home’s protection are always the top priority.

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