Sump Pump Odors and How to Fix Them

May 23, 2020October 28, 2020 Editor

You may be confident in your sump pump reliability but the rainy season proves most homeowners wrong. This is the time where most pumps show their weaknesses. In fact, some homeowners require a sump pump only for rainy months. Those that live in humid places where sump pumps are required all year long know that the pump should be in perfect condition constantly.

Besides a flooded basement, a common indication that there is something wrong with your sump system is the odor. I think a guide on sump pump odors is a good idea, seeing as how most of you need help this time of the year. We’ll go over identifying sump pump odors and how to fix them.

An odor coming from your sump pit or pump should not be ignored. The odor will tell you where to check for issues. Not every odor smells the same, you need to recognize the odor in order to locate the issue. There are several common odors which we will go over in a moment. Some odors indicate an issue that you can fix, for some you will need a professional. Fixing the sump pump will make the smell go away.

Stick around to find out how to identify odors and how to fix them.

Table of Contents

Is there a smell coming from my sump pump?

Now, we need to be absolutely sure that the smell in your home is coming from the sump pump. Usually, the smell is strongest in the basement or it’s only present in the basement. The only thing besides the pump that can smell is your bathroom, so that’s easily recognizable.

This sounds silly but most homeowners know how their pump usually smells. What I’m saying is that the odor will bring a new smell that you will notice. If, besides the usual smell from the pit there is a new odor, you need to investigate.

Once you’re sure that the odor is coming from your pump or pit, you can move on.

How to identify sump pump odors?

As I said, you need to figure out what kind of odor it is, i.e. what does your pump smell like? Obviously, you need to be in your basement and have the sump pump cover opened. After that, you need to activate the dog in you, and focus on the smell.

Sump pump water smells like rotten eggs

The smell coming from your pit may remind you of rotten boiled eggs. Of course, there aren’t any eggs in your pit, so it must be something else. In fact, what you smell is sulfur gas. If you’ve ever been near a sulfur mine, you’ve definitely smelled the same odor.

You already know that sump pumps collect water under the foundation of your house. Well, if a near sewer line is broken, the sewage and your foundation water will merge. Sewer lines contain gases and some nasty things. When sewage enters your sump pit, you’ll notice that horrible sulfur that smells like rotten eggs.

So, there’s nothing wrong with your pump, the issue is with the near sewage line.

Sump pump smells like gasoline

Now, if your sump pit smells like gasoline, gasoline must have made its way into your pit. Gasoline smells like that because it has benzene or a manufacturer added the odor. What I’m saying is, gasoline smell can’t be mistaken for something else.

Because gasoline cannot occur naturally in your sump pit, it must have been spilled nearby. If you are storing gasoline in your basement, that may be the source. Sometimes, a neighbor or workers may have spilled gasoline in the storm drain lines.

Gasoline is also used as a cleaner. Try to remember if a neighbor has used gasoline on his house project. Also, if you have poured gasoline in your garden, it may have merged with the water under the foundation of the house.

Make sure you’ve eliminated every possibility.

Sump pump smells like mildew

As you may know, mildew and mold smell similar. They are both a type of fungus, the difference is mildew doesn’t smell that strong. So, if your sump pump smells like mildew, the odor will probably stay in the basement.

Most fungi need water in order to survive, so the issue is with the stagnant water in your basin. A properly installed sump pump will always leave a small amount of water in the pit. However, the amount of water only be at the bottom at low level.

When the sitting water in the pit is at a higher level than usual that’s the time when mildew forms. So, a sump pit that smells like mildew indicates an issue with your pump. Most likely, the pump isn’t installed properly and it’s not pumping like it should. Or, there is a problem with the float switch and the pump turns off too soon.

Sump pump smells like gas

This case is similar to the rotten eggs smell. In fact, it’s the same odor that you’re smelling. How are they different?

I have said before that there should always be still water in your sump pit. That level of water serves as a protection against underground gases and sewage. When there isn’t any water in your pit and it’s dry, those gases enter your basement.

So, the difference with the rotten eggs smell is that with the rotten eggs there was water in the basin. That means, sewage has merged with your basin water. When your pit is dry, sewage does not enter your basin, it’s just that gases travel to your basin. Don’t be afraid, gases are always present in the basin, the stagnant water stops them from going up.

Sump pit smells like sewer

Unfortunately, for you, what you smell is true. Even though sewer lines are usually reliable, a leak or a crack is a possibility. When that happens, the sewage goes where gravity takes it. In these cases, the sewage may have entered your basin.

You will notice that the water level in the basin is higher than usual because of the sewage. It doesn’t take long for the sewage to start to smell. After a day or two, the smell will be present in your home. Even if you’ve covered your basin well, the smell will still be present in your basement.

House smells musty when it rains

This is the same as mildew. When it rains, your pump has to deal with a lot of water. An inefficient pump or a failed pump will leave stagnant water in the basin. When that happens, your basement will start to smell.

However, if the smell spreads into your house that means that the mildew has been present for quite some time. Or, it means that your basin needs a proper cleaning. Presence of stagnant water for only a day will not make your house smell if the basin isn’t dirty.

As with the mildew smell, this is also an indication that your sump pump isn’t working properly.

Sump pump smells like poop

A poop-like smell from your sump pit is one of those cases that indicate an issue with your sump system. The smell is coming from your drain lines or a floor drain.

As you all know, sump basins are an awfully dirty place. So besides picking up the water, the pump is also picking up debris and dirt. That debris is not necessarily pushed out of your lines, some of it gets stuck and sticks to the inside. That dirt will start smelling like poop, and in due time, it will form a blockage.

So, a poop smell in your basin means that you need to clean the discharge lines.

That’s it with identifying smells, let’s see how to fix them.

Fixing sump pump odors

In the beginning, I said that some of these issues are not fixable with the DIY way. So, I’ll make sure to tell you when a professional is needed.

Rotten eggs smell

We concluded that your pump would smell like rotten eggs in two cases. When the basin water has merged with sewage, and when the basin is dry.

If your basin has water in it and it smells like rotten eggs, there is a problem with a near sewage line. In this case, you must call a professional. Seeing as how most sewer lines are public property, you may need to consult with the local government.

On the other hand, when the rotten eggs smell comes from the dry basin, there is a quick fix. All you need to do is add a mixture of bleach (affiliate link to Amazon) and water in the basin. The water will prevent odors entering your basin and the bleach will kill the remaining smell.

Then, make sure you adjusted your float switch in a way that will prevent cases like this again. In the future always check for water in your basin, when needed, add some.

Gasoline smell

With the gasoline smell, you need to be sure the source of the gasoline is stopped. Remember everything I said about identifying the odor, eliminating every possibility.

Once you’ve done that, you start getting rid of the smell. First, open windows in your basement. If the gas entered your home, open the windows there too. Also, make sure there isn’t anything that can spark a fire nearby.

Getting rid of the smell requires filling your basin with bleach and water. Fill it until your float switch turns on the pump. While the pump is doing its job, use a brush to scrub around in the basin to get rid of odors that stick.

After the pump has cleared the bleach and water, add another batch but only water this time. Stand by and wait for the pump to clear out the water. The gasoline smell should be gone in 2-4 hours.

Mildew smell

Getting rid of the mildew smell means fixing your sump pump first. As I have mentioned, the mildew smell comes from stagnant water in the basin. And there is stagnant water in the basin because the pump isn’t installed properly or it’s failing.

Check out our guide on how to install a sump pump if yours isn’t. If the problem is with a faulty float switch, you need to replace it. Fixing a float switch is quite easy if you follow the manufacturer’s instructions. If the warranty is still in place, use it.

After you’ve made sure that the pump is working properly, use the same process as before. Add bleach and water in the basin until the pump turns on. Scrub around to eliminate any remaining mildew.

Sewer smell

The fact that we used the word ‘unfortunately’ in the section on identifying sump pump odors, may have been a clue for you. I have said that because you can’t fix this by yourself. You must call a professional or contact the local government. Even if you know what you are doing, it’s still a bad idea.

If the sewer malfunction isn’t your doing, try to get compensated for the troubles in your basement.

Poop smell

To get rid of the poop smell you need to clean the drain lines. It doesn’t matter what you’re pumping. If it’s a sump pump line, you clean it. If it’s a sewage line, you still clean it.

Disconnect the drain lines and pour hot water in them. After that add a mixture of bleach and water to get rid of the smell. In the end, wash only with water.

If the smell is coming from a floor drain line, add bleach and water, nothing else.

Seeing as how most fixes require a bleach detergent, let’s see how to make one.

How to make a bleach detergent?

There are two ways you can take here, bleach (affiliate link to Amazon) or vinegar.

A strong vinegar suitable for cleaning sump pumps.
Make sure you add sufficient water.

The strongest detergent is one with bleach. The recommended measurements are a cup of bleach for every gallon of water. However, you add more bleach if you want to make it stronger, at your own risk though.

Vinegar is weaker but there is a lower chance that you may damage your sump pump. There isn’t an exact recipe on how to make this. Just mix water and vinegar, make sure that there is more water than vinegar.

Well, this is the end folks, nothing more to tell you. I hope I helped you with your problems, good luck to you and to your sump pump.