Why Does My Sump Pump Smell?


July 13, 2022

Your sump pump is meant to be a piece of equipment that keeps your basement clean, dry, and odour free. It may well be a cause for concern then if you come to discover that your sump pump is giving off a nasty or foul smell.

Initially you might not know what to think when it comes to a nasty smell coming out of your sump pump. Could it be a fault, a leak, or even something clogged?

We are going to outline some of the main reasons that your sump pump might develop a smell in this article, as well as what you can do to make sure that smell goes away for good.

Reasons Your Sump Pump Might Smell:


There are plenty of reasons that your sump pump might smell, and none of them are particularly pleasant – as you might have expected from the smell coming from the pump.

So, what are the main reasons your pump could smell, and how could they be fixed?

Clogs and Blockages:

Sump pump check valve blocked

The first (and most obvious) reason that your pump might have developed a nasty smell is because your pump has become blocked up or clogged, and now isn’t draining correctly or is just retaining something nasty which you would rather have pumped out of your basement.

Ruling out the obvious, if your pump is emitting a smell that could be described as burning, or as hot metal, it could be the case that your pump is blocked or impeded so badly that when it’s trying to work, the motor is slowly burning itself out. If this is the case then it’s important that you contact an engineer as soon as possible to avoid further damage or flooding.

If the smell emanating from the pump is foul, or more ‘natural’ smelling than that of an overworked motor though, you could well have something in your sump pump that shouldn’t be there and is now decaying, letting off a natural bad smell.

This could be anything. We have in the past seen fatty deposits from dishwasher water build up over time within the pump cause a blockage and bad smells, garden waste like leaves and dirt making their way into the sump pump system, or even other general waste from a basement finding their way into a pumps system and clogging it up.

In any event, a clog or blockage within the pump of this kind will need to be examined and fixed by a trained basement sump and pump specialist to bring your pump back into healthy, working order.

Stagnant Water:


Stagnant water is a common reason that a pump might give off a foul smell, especially in the summer.

This is because your sump pump contains what is known as a float switch. This float switch triggers the flushing mechanism within your pump once the tank fills to a certain level, removing the floodwater from your property and flushing it away safely.

This is all well and good in the colder, wetter months of the year, but during the lengthy dry spells we see in the summer it can be a potential issue.

Stagnant water sitting within your sump pump can easily provide different mould or fungi ideal grounds which they can grow and spread within.

Often, this stagnant water (if left in your tank long enough) can be enough to create a really horrible smell. Of course, this could be one of the easier fixes on the list when it comes to removing a nasty, putrid smell from your sump pump.

Simply by adding enough water into your sump pumps tank that the float switch is triggered, you may be able to remove that stagnant water and the associated smell.

With that in mind, it can be worth consulting a sump pump specialist regarding what further steps you can take to help eliminate smells in your sump pump without damaging the pump itself.   

Sewage Infiltration:

A rather nasty reason that your sump pump might emit a horrible smell is thanks to sewage making its way into the sump pumps intake system.

Sewage infiltration within a sump pump usually occurs when sewage pipes occupying the same space near the sump pump burst or break, and the sewage travelling through said pipes finds its way into the drainage channels designed to collect floodwater permeating your basement’s walls and floors.

Obviously, there is a higher chance of this happening if your property happens to make use of a sewage pump, as if the sewage pump (usually situated in the basement along with the sump pump) breaks down or floods, then there is every chance wastewater and other fluids could be caught by the sump pump.

Obviously, the smells given off by a sump pump retaining sewage are going to be horrible, made even worse if combined with stagnant water and heat during the summer.

In situations where sewage is infiltrating your sump pump, you will need a below ground pump expert to examine your sump pump, and potentially your sewage pump too. You may even need to make use of a basement waterproofing expert to re-examine your waterproofing system, in conjunction with a plumber who can inspect your properties plumbing to find where the fault allowing for sewage to escape is happening.

Discover the Root of Your Sump Pumps Foul Smell:

If you own a sump pump that is letting off a terrible smell, but aren’t sure why (or you can’t bear to find out), our team of well trained experts are ready to take on the case.

You can arrange with our team to have a routine inspection or service carried out on your below ground pumps at any time that’s convenient to you – and keep that appointment in place so you never fall behind on your sump pumps maintenance again.

Just fill in one of our contact forms online here, or call 0800 019 9949 to arrange for our team of experts to visit you, and get to the bottom of what’s causing your sump pump to smell.


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