Turning on a sump pump depends on whether yours is automatic or manual
Most sump pumps are automatic and turn on by themselves when water reaches a certain level in the pit. You do not flip a switch to start them. Instead, you check that the pump is plugged in, the outlet works, and the float switch (a ball or arm that rises with water) moves freely. If your pump is manual, you turn it on by pressing a button or flipping a switch on the pump itself or on a control panel mounted nearby.
The first step is to know which type you have. Look at the pump in the sump pit. If you see a ball or arm attached to the pump that floats up and down with the water level, it is automatic. If you see a button or switch on the pump housing or on a wall-mounted control box, it is manual. Your pump's manual or the label on the pump will also say which type it is.
If your pump has never run before, or if it has not run in months, test it before you need it. Pour water slowly into the sump pit until the float rises. The pump should start on its own if it is automatic, or you should press the button if it is manual. Listen for the motor to hum and feel for vibration. If nothing happens, the pump may not be plugged in, the outlet may be dead, or the pump itself may have failed.
Key Takeaways
- Automatic sump pumps start on their own when water rises to a set level and do not need you to turn them on manually.
- Manual sump pumps require you to press a button or flip a switch to start them, usually located on the pump or a nearby control panel.
- Before relying on your pump, test it by pouring water into the sump pit and listening for the motor to start.
- A pump that does not start when tested may be unplugged, connected to a dead outlet, or broken and needs a professional inspection.
- Check that the float switch moves freely and is not stuck against the pump housing, which prevents automatic pumps from turning on.
Check that the pump is plugged in and the outlet has power
This is the most common reason a sump pump does not start. Follow the power cord from the pump to the outlet. Make sure the plug is fully inserted into the socket. If it is loose, push it in firmly. Then plug in a lamp or phone charger into the same outlet to confirm the outlet itself works. If the lamp does not turn on, the outlet is dead and you need an electrician to check the circuit breaker or the outlet wiring.
Some sump pump outlets are on a dedicated circuit breaker. If the outlet is dead, go to your electrical panel and look for a breaker labeled "sump pump" or "basement." If the switch is in the OFF position or in the middle, flip it fully to ON. If it flips back to OFF or to the middle on its own, the circuit is overloaded or the pump is drawing too much power, and you should call an electrician before using the pump again.
Make sure the float switch moves freely
The float switch is the part that tells an automatic pump when to turn on. It is usually a ball or an arm attached to the pump by a rod or cable. As water rises in the pit, the float rises with it. When the float reaches a certain height, it triggers the pump to start. If the float is stuck against the pump housing, wedged against the pit wall, or tangled in a cord, it cannot rise and the pump will not turn on.
Reach into the sump pit (if it is safe to do so and the water is not too high) and gently move the float up and down by hand. It should move smoothly without resistance. If it is stuck, try to free it by hand. If the float is cracked, the rod is bent, or the switch itself is broken, the pump will not start automatically and you will need to replace the float switch or the pump.
Test the pump before you need it in an emergency
The best time to learn whether your pump works is not during a heavy rain or a basement flood. Pour a bucket of water slowly into the sump pit and watch what happens. For an automatic pump, the water level should rise, the float should rise with it, and the pump should start within a few seconds. You will hear the motor hum and feel the pump vibrate. Water should flow out of the discharge pipe (the pipe that carries water away from the house).
For a manual pump, pour the water in and then press the button or flip the switch. The pump should start when ready. If it does not, stop and do not use the pump until you know why. A pump that fails a test will fail when you need it most.
After the test, let the pit drain completely. The pump should turn off on its own if it is automatic. If it stays on, the float switch may be stuck or the pump may be running continuously, which will wear it out and waste electricity. Call a professional to inspect it.
Know the difference between automatic and manual operation
An automatic pump has a float switch that responds to water level. You do not control it. Once it is plugged in and the float moves freely, it will turn on whenever water reaches the trigger point and turn off when the water drains below that point. Your job is to keep the pit clean, make sure nothing blocks the float, and test it occasionally. You should never unplug an automatic pump unless you are doing maintenance, because it needs to be ready to run at any time.
A manual pump requires you to press a button or flip a switch every time you want it to run. This is useful if you want to control when the pump operates, but it means you have to be home and remember to turn it on. Some people use manual pumps as a backup to an automatic pump, or in situations where the water level does not rise high enough to trigger the automatic float. If you have a manual pump, test the button or switch regularly to make sure it works.
What to do if the pump will not start
If you have tested the pump and it does not start, work through these steps in order. First, make sure the plug is fully inserted and the outlet has power by testing with another device. Second, check that the float switch moves freely and is not stuck. Third, listen carefully when you turn on the outlet—if you hear a buzzing sound but the motor does not spin, the pump may be jammed or the motor may be burned out.
If the outlet is dead, check the circuit breaker. If the breaker is tripped, flip it back on. If it trips again when ready, do not keep flipping it—call an electrician, because the circuit may be overloaded or the pump may be drawing too much current. If the float moves freely, the outlet works, and the pump still does not start, the pump itself has failed and needs to be replaced. This is a job for a professional, because you will need to remove the old pump, install a new one, and make sure the discharge pipe is connected correctly.
Maintain your pump so it stays ready to run
A sump pump that sits unused for months can fail when you need it. Every three to six months, pour water into the pit and let the pump run for a minute or two. This keeps the motor lubricated and the float switch responsive. If the pump has not run in a long time, it may need a few cycles before it works smoothly again.
Keep the sump pit clean. Debris, sediment, and dirt can clog the pump intake and jam the float. If the pit is very dirty, you may need to pump it out and rinse it before testing. Check the discharge pipe to make sure water is flowing out and not backing up into the pit. If water is backing up, the pipe may be frozen, clogged, or disconnected, and the pump will not be able to drain the pit even if it is running.
Frequently Asked Questions
Do I need to turn on my sump pump before it rains?
No. An automatic pump turns on by itself when water reaches the float switch, so you do not need to do anything before rain. A manual pump requires you to turn it on, but only if water is already in the pit. Check your pit before heavy rain to see if water is collecting, and turn on a manual pump if needed.
What if my sump pump runs constantly?
A pump that runs without stopping is usually stuck in the ON position because the float switch is jammed or the water level is not dropping. Turn off the pump when ready and check that the float moves freely. If the float is stuck, free it by hand. If the water level is not dropping, the discharge pipe may be clogged or frozen. Do not leave the pump running continuously—it will overheat and fail.
Can I use an extension cord with my sump pump?
No. Sump pumps draw a lot of power and extension cords can overheat and cause fires. Plug the pump directly into a wall outlet. If the outlet is too far away, hire an electrician to install a new outlet closer to the pump or to run a permanent power line.
What should I do if the pump is making a strange noise?
Strange noises usually mean something is wrong. A grinding or squealing sound may mean the motor bearings are worn out. A rattling sound may mean something is loose inside the pump or the pump is vibrating against the pit. Turn off the pump and do not use it until you know what is causing the noise. Call a professional to inspect it.
Is it normal for the pump to run during heavy rain?
Yes. During heavy rain, water enters the pit faster than the pump can drain it, so the pump may run almost continuously. This is normal and means the pump is working as designed. However, if the water level keeps rising even while the pump is running, the pump may not be powerful enough for the amount of water, or the discharge pipe may be clogged.