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  • Writer's pictureIryna B

What to do When Sump Pump Overflows?

If your basement sump pump is overflowing, there must be a cause for this.




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Sump pump is a reliable piece of equipment. But when it does fail, it can cause serious damage.


The most common cause of sump pump overflow is rain and power outage that happen at the same time.


This way, the water keeps accumulating in the drainage system and the sump pump can't push it out.


Steps to Take if Sump Pump Overflows



1. Make Sure it Has Power


Power outages/lost power is the number one reason for the sump pump overflow. In some cases your home may have the power, but sump pump fuse may be blown or tripped circuit may be causing the issue.


Remember electricity is dangerous, talk to an expert if you are not sure what to do.


Installing a battery backup pump will keep your sump pump working even when there is no power.


2. Restart the Sum Pump


Unplug the sump pump for a couple of minutes and plug it back in. In some cases this may resolve the issue.


Either way, make sure to talk to get your sump pump checked by an expert, some cities offer sump pump rebates – Toronto, Mississauga, Burlington, Oakville and more.



Infographics showing the sump pump elements - float switch, check valve, discharge pipe and more. Image Source: Wikipedia


3. Restart the Motor


Sump pump may not be turning on due to a mechanical issue.


Disconnect the sump pump from electricity, try pulling upwards on the float switch. If restarting the sump pump and the motor doesn’t work, these may be the signs of a mechanical issue.



4. Check the Overflow Valve (Check Valve)

This mechanism prevents the water that is pumped out from entering the sump basin again. It may not be functioning properly if it gets blocked. So check the overflow valve for debris. In some cases, it may be the pipe over the valve that is clogged.



Image showing an example of sump pump float switch. Image source: Canadian Tire


5. Check the Float Switch

Check the float switch. It may be mechanically blocked with debris. In case the float switch can’t move freely, it won’t activate the sump pump.


6. Clear the Weeping Hole

Sump pumps have a small hole drilled on the pipe used for discharge. When sump pump turns on, this hole is used to remove the air. This prevents the lock up of the equipment.


If you find the weeping hole blocked, clear it out.


Image showing the sump pump impeller. Image source:


7. Check the Impeller & Basin

Always unplug the sump pump before working with it.


The impeller connects the sump pump with the discharge line.

Lift up the sump pump to allow access to the impeller and if it’s blocked, clear it our from debris or anything else stuck there.


8. Sump Pump Discharge Line Cleaning

To access the discharge line – unplug the sump pump and take it our the sump basin. Try snaking the discharge line from the inside.


Check if the sump pump discharge line is blocked from the outside the house – it may be clogged with leaves, other debris, mice. It may also be frozen.


What Else Might be Causing Sump Pump to Overflow?

  1. Too much water – in some cases you may simply have too much water flowing into the sump pump. Some properties require multiple sump pumps installed.

  2. Sump Pump Size – in some cases it’s the wrong sump pump size that is causing the problem. For example, if the sump pump is too small, it will be running for prolonged periods of time eventually causing the sump pump to break.


Image showing battery backup sump pump. Image source: Home Depot.


How to Prevent Sump Pump Overflow?

  1. Sump Pump Overflow Alarm – is a device used to notify you when the water level in the sump pit is too high. This way you can address this issue before it turns into a problem.

  2. Battery Backup Pump – a sump pump that is powered by a battery. This helps prevent the most common cause of sump pump not working – power outage. When your sump pump is powered by a battery, it can continue to operate even if the power is out.

Written by Aquamaster Basement Waterproofing. Get one of our experts on the phone today to discuss your sump pump overflow issue, options to install, repair or replace the sump pump and other basement waterproofing options.

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