How often should I test my sump pump?

Several times a year, and always before a wet season. Pour water into the pit and confirm the pump starts, moves the water out, and stops on its own. Testing takes two minutes and is the highest-value thing you can do here.

My pump runs constantly even when it's dry. Why?

Usually a stuck float, a failed check valve letting discharged water flow back into the pit, or groundwater genuinely entering at that rate. Constant running wears a pump out fast, so it's worth diagnosing.

Do I need a battery backup?

It's worth serious consideration if a basement flood would be costly for you, especially since storms that bring the most water also bring power outages — precisely when the pump is needed most.

Basements & Sump Pumps

Sump Pump Problems: Before the Next Heavy Rain

The pump won't run, runs constantly, or cycles strangely — and the basement depends on it working.

A homeowner guide — what may be happening, and what to do next.

If this is an emergency

Uncontrolled water, sewage entering the home, a suspected gas leak, or water near electrical equipment all need immediate action. Shut off the water at the main if it is safe to reach, keep everyone away from hazards, and contact your local emergency services, your utility provider, or a licensed professional as appropriate.

What's happening?

A sump pump sits in a pit at the lowest point of a basement or crawlspace. Groundwater collects there, a float switch senses the rising level, and the pump sends the water out through a discharge line away from the foundation. It's a simple system with a small number of failure points.

The two failure modes to understand are opposite. A pump that won't run at all means water will rise until it floods — usually caused by a power problem, a stuck float, or a failed motor. A pump that runs constantly or cycles rapidly is either being fed more water than it can handle, or its switch or check valve is faulty, and running dry wears it out quickly. Both deserve attention before the next storm rather than during it.

Common signs

Symptoms homeowners notice

The pump doesn't run even with water in the pit
It runs continuously, or cycles on and off rapidly
Loud grinding, rattling, or vibration
Water in the pit at a higher level than usual
Dampness, staining, or standing water on the basement floor
A visible power problem — unplugged pump, tripped GFCI, or tripped breaker
A discharge line that's frozen, blocked, or disconnected

Possible causes

From simple to more serious — not a diagnosis of your specific situation

A stuck or misaligned float switch: The most common cause of a pump that won't start or won't stop. Debris or a pit wall can trap the float.
A power problem: Unplugged pump, tripped GFCI outlet, or tripped breaker. Always check this first.
A blocked or frozen discharge line: Water can't leave, so the pump runs without lowering the level.
A failed check valve: Water flows back into the pit after each cycle, making the pump run repeatedly.
A clogged intake or a debris-filled pit: Silt, gravel, and sediment restrict the pump.
A failed motor or impeller: End of service life, often accelerated by running dry or running constantly.
An undersized pump: Not enough capacity for the water volume the site actually produces.
High groundwater or drainage problems: Gutters, downspouts, and grading discharging next to the foundation overload the system.

How urgent is it?

High — address promptly

A failed sump pump may cause no problems at all until it rains — and then it causes a flooded basement. Check it before you need it.

Low
Medium
High
Emergency

What you can safely check

Simple observations and low-risk checks. None of these require tools you don't have or work you aren't qualified for.

Confirm the pump is plugged in and that its outlet, GFCI, and breaker have not tripped.
Look into the pit with a flashlight for debris, silt, or a float caught against the wall.
Test it by slowly pouring water into the pit and watching whether the pump starts and stops properly.
Follow the discharge line outside and check that it's clear, unfrozen, and directing water away from the foundation.
Check that downspouts and grading move water away from the house.
Note whether there's a battery backup and whether its indicator shows a fault.
Listen to the sound of a cycle so you can describe any change.

What not to do

These are the actions that turn a manageable problem into an expensive or dangerous one.

Avoid these

Don't reach into a pit containing water while the pump is plugged in. Unplug it first — this is water and electricity together.
Don't repeatedly reset a tripping breaker or GFCI. It's protecting you from a fault in the pump or its circuit.
Don't run an extension cord to a sump pump as a long-term arrangement, and don't remove a grounding pin.
Don't use an open flame or heat gun to thaw a frozen discharge line.
Don't remove or plug a check valve, and don't reduce the discharge pipe size.
Don't discharge sump water into a sanitary sewer line where that's prohibited — it's a code violation in many places.
Don't leave a known-failing pump in place through a storm season.

Can I fix this myself?

Safe to check

Observation and low-risk checks most homeowners can make.

Checking power, the GFCI, and the breaker
Looking into the pit with a flashlight
Testing the pump by adding water and watching a full cycle
Inspecting the exterior discharge point
Checking gutters, downspouts, and grading

Proceed with caution

Minor actions where instructions must be followed carefully.

Removing visible debris from the pit with the pump unplugged
Extending a surface discharge line away from the foundation

Call a professional

Regulated, hazardous, or specialized work. Don't attempt it.

Pump replacement and float switch work
Electrical circuit and GFCI work
Check valve and discharge piping repairs
Backup system installation
Assessing recurring basement water problems

When to call a licensed plumber

Clear signals it's time for professional help

The pump won't run and it isn't a power or float issue you can see
It runs constantly, or cycles every few seconds
The breaker or GFCI trips when it runs
You're getting water on the floor despite the pump running
You want a backup pump or battery backup assessed
You aren't sure the pump is sized correctly for your site

Not sure yet? Read our general guidance on when a plumber is needed.

Questions to ask your plumber

Worth covering before you authorize any work.

Before work starts

1Is the pump correctly sized for the water volume here?
2Is the discharge line configured correctly, and does it terminate far enough from the foundation?
3Would a battery backup or a secondary pump be worthwhile in this basement?
4Is the check valve functioning?
5Does the dedicated circuit and outlet meet current requirements?
6How often should this be tested and serviced?
7Are you licensed to do this type of work in my area, and can I see your license number?
8Do you carry liability insurance and workers' compensation?
9Will you provide a written estimate before starting work?
10Is a diagnostic or trip fee charged, and is it applied to the repair if I go ahead?
11Does this work require a permit or an inspection?
12What warranty applies to the labor, and what warranty applies to the parts?

What could affect the cost?

We don't publish prices, because real quotes depend on your home, your area, and what's found on site. These are the variables that move the number.

Cost drivers

Repair vs. replacement: A float switch or check valve is a modest repair; a new pump is a larger one.
Pump type and capacity: Pedestal, submersible, and higher-capacity pumps differ considerably.
Backup systems: Battery or water-powered backup pumps add equipment and installation cost — and prevent the worst outcome.
Discharge line work: Re-routing, extending, or repairing a buried discharge line involves excavation.
Electrical work: A dedicated circuit or GFCI outlet may need an electrician.
Pit condition: A pit that needs cleaning out, or a basin that needs replacing, adds labor.
Emergency timing: Mid-storm service costs more than a scheduled visit before the season.

More detail on how plumbing work is priced: Plumbing costs — what to expect.

Common questions

How often should I test my sump pump?: Several times a year, and always before a wet season. Pour water into the pit and confirm the pump starts, moves the water out, and stops on its own. Testing takes two minutes and is the highest-value thing you can do here.
My pump runs constantly even when it's dry. Why?: Usually a stuck float, a failed check valve letting discharged water flow back into the pit, or groundwater genuinely entering at that rate. Constant running wears a pump out fast, so it's worth diagnosing.
Do I need a battery backup?: It's worth serious consideration if a basement flood would be costly for you, especially since storms that bring the most water also bring power outages — precisely when the pump is needed most.

This guide is general educational information, not a diagnosis of your specific situation. Plumbing codes, regulations, and licensing requirements vary by state and locality.