Before you begin. This procedure is general reference information, not professional advice. Equipment varies by manufacturer, model, and year. Always follow the documentation supplied with your equipment — where it differs from this page, follow the manufacturer. Verify that you have the tools, the working conditions, and the ability to do this task safely. If anything is unclear, if the equipment is damaged, or if the task exceeds your experience, stop and use a qualified professional. You are responsible for your own safety and for the outcome. This site accepts no liability for any loss, damage, or injury arising from the use of this information.
Specifications marked unverified could not be traced to a manufacturer source. Do not rely on them — obtain the value from your equipment documentation.
Summary
A sump pump spends most of its life doing nothing, and then it has one job on one bad night. The failure people actually meet is not a burnt-out motor: it is a float that cannot move because debris has built up around it, or a discharge line blocked with ice or leaves, or a plug that worked its way loose months ago. All three are visible in ten minutes, and all three are invisible until you go and look. Zoeller's own installation instructions ask for an inspection and test of the system at least every three months, which is roughly four visits a year for a machine whose failure costs you a basement.
The test on this page is the honest one: fill the pit with water and watch the pump do what it does when it matters. It is not the same as lifting the float by hand, which proves only that the switch closes. The page covers the fill test, what to look at while the power is disconnected, and where to stop. It does not print a discharge pipe size, a switch level, a temperature limit or an electrical rating, because every one of those belongs to your pump and your installation, and the label on the pump has them. Changing the discharge line is not on this page either — that is regulated work and it belongs to a plumber.
Safety
DO NOT TOUCH THE PUMP OR THE WATER WHEN THE PUMP HAS ELECTRICAL POWER.
Contact with electrical parts through water can kill you.
Necessary equipment
| Item | Note |
|---|---|
| Rubber gloves | The gloves must cover your wrists. |
| Bucket | Use a bucket that holds at least 10 litres. |
| Flashlight | A sump pit is a dark space. |
| Old towels | The towels keep the water off the floor. |
| Notebook or maintenance record | Record the date of each test. |
| Clean water material | Water from a tap is sufficient. |
Specifications
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.
Prepare the area
Estimated 3 min to 5 min
PUT ON THE GLOVES BEFORE YOU TOUCH THE SUMP PIT.
Water in a sump pit can contain bacteria.
- Put on the rubber gloves.<1mReport a problem with step 1, Prepare the area
- Find the sump pit in the basement or the crawl space.1mReport a problem with step 2, Prepare the area
- Put the old towels around the sump pit.<1mReport a problem with step 3, Prepare the area
- Remove the cover from the sump pit.<1mReport a problem with step 4, Prepare the area
- The pump makers say that every sump pit needs a cover.
- A cover keeps debris out of the pit and prevents an accident.
Disconnect the electrical power
Estimated under a minute
DISCONNECT THE PUMP FROM THE OUTLET BEFORE YOU PUT YOUR HAND INTO THE SUMP PIT.
The pump can start without warning and injure your hand.
DO NOT TOUCH THE PLUG WITH WET HANDS.
Water on your skin can cause a fatal electric shock.
- Disconnect the pump from the outlet.<1mReport a problem with step 1, Disconnect the electrical power
- Make sure that your hands are dry.<1mReport a problem with step 2, Disconnect the electrical power
- Make sure that the floor around the outlet has no water on it.<1mReport a problem with step 3, Disconnect the electrical power
Examine the pump and the float
Estimated 7 min to 15 min
- Look into the sump pit with the flashlight.<1mReport a problem with step 1, Examine the pump and the float
- Remove stones, dirt and other debris from the sump pit.2mReport a problem with step 2, Examine the pump and the float
- The pump makers say that debris around the float is a usual cause of a failure.
- Debris can hold the float in one position.
NEVER LIFT THE PUMP BY ITS POWER CORD.
Damage to the cord can expose the wires and cause a fatal electric shock.
- Examine the power cord of the pump for damage.<1mReport a problem with step 3, Examine the pump and the float
- Move the float through its full travel with a gloved hand.<1mReport a problem with step 4, Examine the pump and the float
- The float must move freely.
- The float must have clearance from the side of the sump pit.
- The float must have clearance from the discharge pipe.
- Find the outlet of the discharge pipe outside the building.2mReport a problem with step 5, Examine the pump and the float
- Remove ice, leaves and other debris from the outlet of the discharge pipe.2mReport a problem with step 6, Examine the pump and the float
- The pump makers say to examine the discharge line for ice when it goes through a cold space.
Do the fill test
Estimated 9 min to 12 min
NEVER USE AN EXTENSION CORD FOR A SUMP PUMP.
A damaged extension cord in a wet basement can cause a fatal electric shock.
- Connect the pump to the outlet.<1mReport a problem with step 1, Do the fill test
- Keep your hands away from the sump pit.<1mReport a problem with step 2, Do the fill test
DO NOT LET THE PUMP RUN WITH NO WATER IN THE SUMP PIT.
A pump that runs dry can cause damage to the seal.
- Pour water slowly into the sump pit.1mReport a problem with step 3, Do the fill test
- Continue to pour water until the float rises.2mReport a problem with step 4, Do the fill test
- Make sure that the pump starts.<1mReport a problem with step 5, Do the fill test
- Make sure that the water level decreases.<1mReport a problem with step 6, Do the fill test
- Make sure that water flows from the discharge pipe outside the building.1mReport a problem with step 7, Do the fill test
- Make sure that the pump stops after the water level decreases.<1mReport a problem with step 8, Do the fill test
- A pump that continues to run has a float that cannot move to its low position.
- Listen for unusual noise from the pump.<1mReport a problem with step 9, Do the fill test
- Do the fill procedure two more times.3mReport a problem with step 10, Do the fill test
- The pump makers say to run several cycles of water through the system.
After the job
Estimated 3 min
Source: Installation Instructions, Recommended Models (form FM2676, P/N 151797-B) · tier 1 · accessed 2026-07-29
- Install the cover on the sump pit.<1mReport a problem with step 1, After the job
- Make sure that the plug of the pump is fully in the outlet.<1mReport a problem with step 2, After the job
- Remove the gloves. Wash your hands.1mReport a problem with step 3, After the job
- Record the date of the test.<1mReport a problem with step 4, After the job
- Do this test again after three months.<1mReport a problem with step 5, After the job
Terminology
This page uses one term for each item and holds it throughout, as ASD-STE100 requires. Equipment sellers and other guides use the names below for the same parts.
- sump pump
- Also called: basement pump, cellar pump, water pump in the basement, sub pump, submersible pump
- sump pit
- Also called: sump basin, sump hole, sump well, crock, the hole in the basement floor
- float switch
- Also called: float, float ball, tether switch, level switch, bobber
- discharge pipe
- Also called: discharge line, outlet pipe, sump pump pipe, drain line
- check valve
- Also called: one way valve, non-return valve, backflow valve
- impeller
- Also called: pump wheel, propeller, fan in the pump
When to use a professional
Stop if the pump does not start when the float rises. Stop if the pump makes a noise but moves no water. Stop if the pump starts and stops many times each minute. Stop if the pump moves water slowly. Speak to a licensed plumber or a pump dealer.
Do not open the pump. Do not remove the base of the pump. The pump makers say that an authorized service center must do a repair. Do not change the discharge pipe. Do not change the route of the water from the discharge pipe. Local rules control where that water goes.
Never work in a basement that has water on the floor while the equipment has electrical power. Speak to a licensed electrician about the outlet that supplies the pump. The pump makers say that a ground-fault circuit interrupter on that outlet gives more safety. A licensed electrician must do any change to the outlet.
Common questions
How often should I test my sump pump?
Zoeller's installation instructions put it plainly in their list of things to do: inspect and test the system for proper operation at least every three months. That is the number this page prints, and it comes from a pump maker rather than from a rule of thumb. Liberty Pumps does not give an interval at all in its S30-Series manual; it says to check the pump frequently for debris and build-up that may interfere with the pump or float switch. Four visits a year is a reasonable reading of both, and the visit before the wet season is the one that matters most.
How do I test a sump pump?
Fill the pit and watch what happens. Pour water in slowly until the float rises, and the pump should start on its own, drop the water level, push water out of the discharge pipe outside, and then stop. Liberty Pumps describes the same idea for a new installation: run several cycles of water through the system to verify correct control operation. Doing it three times in a row is worth the extra five minutes, because a switch that sticks does not always stick on the first cycle.
Can I just lift the float by hand instead?
You can, but it is a weaker test and it puts your hand somewhere the manufacturers tell you not to put it. Lifting the float proves the switch closes and the motor turns. It does not prove that the float can rise on its own, which is the thing that actually fails when debris builds up around it, and it does not prove that water reaches the outside. Both Zoeller and Liberty Pumps say to disconnect the pump from its power source before handling it, and a hand in a pit with a pump that can start is exactly the situation that warning is about.
My sump pump hums but no water comes out. What is wrong?
Liberty Pumps lists the usual causes for a pump that runs or hums without pumping: the discharge line is blocked or restricted, the check valve is stuck closed or installed backward, a gate or ball valve is closed, the lift height is beyond what the pump can do, or the impeller or inlet screen is obstructed. It also makes the seasonal point that the blockage can be ice, where the discharge line passes through or into a cold area. The outdoor end of the pipe is the first place to look and the easiest to clear. Anything inside the pump is a job for a service centre, not for you.
Can I plug a sump pump into an extension cord?
No. Zoeller's list of dos and don'ts says it in those words: do not use an extension cord with a sump pump. Their reasoning is that a cord that is too long or too light does not deliver enough voltage to the motor, and that a damaged cord or a connection end lying in a wet or damp area is a safety hazard. The electrical supply is supposed to be within reach of the pump's own cord. If it is not, that is a conversation with a licensed electrician, not a trip to buy a longer lead.
The pump runs and never shuts off. What does that mean?
Usually the float cannot get back down. Liberty Pumps' troubleshooting table gives the cause as the float switch being unable to move to its off position because of interference with the side of the basin or another obstruction, and the fix as repositioning the pump or the switch so the float has adequate clearance for free movement. A defective switch is the other possibility, and that is a replacement rather than an adjustment. Either way, unplug the pump before you reach in.
Should the outlet the pump plugs into be a GFCI?
Zoeller's own instructions say that for added safety the receptacle may be protected with a ground-fault circuit interrupter, and separately that each electrical outlet should be checked for ground with a listed circuit analyzer, calling a qualified licensed electrician if it is not correct. Note the wording: added safety, not a substitute for the pump being properly grounded through its three-prong plug. What you can do without an electrician is test a GFCI outlet that is already there. Changing what protects the circuit is not homeowner work.
Related procedures
- How to clean out a sump pump pit and check the check valve so the pump stops cycling
- How to test a sump pump battery backup and check the battery
- How do I check if my water heater's pressure relief valve pipe is installed correctly
- How to connect and unclog a dehumidifier drain hose so it doesn't fill the bucket
- Why a leaf blower loses power, and how to clear a blocked intake
- How to clear a blocked condensate drain on a central air conditioner
- Decide why water is standing in the bottom of a dishwasher
- How to unclog a slow or blocked drain in a sink, bathtub or shower
Sources
Every specification on this page is traced to one of these sources. Tier 1 is a manufacturer document, a published standard, or a government safety authority. See Standards for the full tiering rule.
- Tier 1Installation Instructions, Recommended Models (form FM2676, P/N 151797-B)
- Tier 1Installation Manual — S30-Series Submersible Sump Pumps (document 7175000H)
Revision history
Current version 1 · updated 2026-07-29 · next review due 2027-07-29
- v1 · 2026-07-29First draft. Built from two manufacturer documents read directly from the publishers' own sites: Zoeller FM2676 installation instructions (July 2026) and the Liberty Pumps S30-Series installation manual. The test interval is Zoeller's own figure. Every step written independently in Simplified Technical English from the meaning rather than the wording. Discharge routing, pump disassembly and any change to the electrical supply are refused and routed to a licensed trade in the professional boundary. No electrical rating, temperature limit, pipe size or switch level publishes as a number: every one of them is per-installation and the page sends the reader to the pump label or the manufacturer. Registering the sources themselves is refused to a delegate (config.json -> models.never_delegate_human), so the two entries are held in data/sources-additions-test-a-sump-pump.json for merge into data/sources.json. That merge is the only thing between this record and a pass: with the two entries merged, the record passes all thirteen checks with two warnings (no spec_key on the interval, and zero related links).
Corrections to this page are listed in the public corrections log. Reports that are credible and not yet verified are listed in the public errata register, and an open one renders above the step it concerns.
Comments and corrections
Found an error? A correction with a manufacturer source is applied and logged publicly. You can also write to corrections@fixchecklist.com.
Every step above carries its own report control, which tags the report with that step so a correction reaches the right place. For anything about the procedure as a whole — the order of the sections, a step that is missing, something that did not match your equipment — use this: report something about this whole procedure.