How to fix Swamp Cooler Smell

How to fix swamp cooler smell. Swamp coolers are the ultimate breeding ground for bacteria and bad odors.

All the dust that comes in from the outside collects on the air filters and the wet water pads.

After a few days in the summer heat, the smell is inevitable.

Swamp coolers stink naturally. Especially, when they’re used a lot.

So, let’s have a look at how you can get rid of the smell by cleaning your swamp cooler.

Quick answer: You can fix swamp cooler smell by cleaning or replacing the water pads. Also, clean the water tank with a vinegar and water solution. Dust the air filters. And, if needed, soak the water hose in a bucket full of water and add half a cup of vinegar or bleach.

How to remove the smell from your swamp cooler

To clean your swamp cooler, you will need at least

  • access to water
  • a sponge

Ideally, you also grab a vacuum cleaner. If you want to brute-force rinse your entire swamp cleaner, a garden hose is helpful as well, but it’s optional.

1. Clean the water pads

Most of the smell in a swamp cooler comes from the water pads. So, the first, and by far most important step is to clean the pads.

Open the backside of your swamp cooler. You might need a screwdriver.

Once the back side of your swamp cooler is open, you should be able to take out the water pads easily.

Sometimes, the water pads barely fit inside the swamp cooler and are stuck. So, you need to pull them out with force.

Water pads are never fixed to the swamp cooler, so don’t worry about breaking off anything.

Rinse the water pads using a garden hose

Once the water pads are out, the simplest way to clean the water pads is to rinse them with your garden hose.

You will see a lot of dirt coming out of the water pads.

Soak the water pads in the tub

Alternatively, you can soak the swamp cooler’s pads in your bathtub. If you want, you can add vinegar or soap to dissolve more stuff and kill off bacteria.

Let the sponge pads soak for an hour.

After that, rinse the water pads thoroughly.

Optional: Dry the pads

If you actively use your swamp cooler, there is no need to dry the water pads.

The swamp cooler will soak the pads anyways.

But if you want to store away your swamp cooler for the colder season, you should dry your water pads thoroughly before putting them in the cooler again.

Dry them in the sun. Alternatively, use a drier or heated floor to dry the pads.

Insert the water pads

Insert the water pads only after the cleaning of the entire swamp cooler is done.

So, wait for reinsertion, until the end.

To insert the water pads, just force them back into place. During rinsing or soaking, water pads can change shape and size a bit. So, they might not fit well initially.

But over time, they will readapt to their original size.

Alternatively: Replace the pads

Instead of cleaning the water pads, you can also just replace them entirely.

A full replacement is, of course, better than cleaning. New sponge pads don’t hold any leftover bacteria. And they will last you much longer before they start smelling.

The hard part is just finding fitting parts for swamp coolers.

Online, I found one person complaining:

“You say replace the pads like it’s easy to find the correct pad for your cooler model”

But actually, you don’t need to find fitting replacement pads. You can just cut them to size.

I recommend getting this evaporator water pad 2-pack (click here to view them on amazon).

These pads suit almost any swamp cooler.  And if you have a smaller model, just cut off bits until they fit.

Replacing the pads obviously costs some money. But if you compare that to hiring an HVAC technician, who usually charges beyond $80, you still save a lot of money!

2. Clean the air filters

Some swamp coolers have built-in air filters. You should be able to access the air filter once the back side of the swamp cooler is open.

Usually, the air filters don’t need replacement, since they do not get wet themselves and, therefore, don’t cause the smell directly.

There are two ways to clean the air filter:

Dry clean air filters using a brush

To clean dusty air filters, I always recommend cleaning them using a dry brush. You can use an old toothbrush or something similar.

Sometimes it is even possible to pull off the dust using your bare hands.

I always recommend dry-brush cleaning, because it does not increase bacteria growth.

Air filters collect bacteria, dust, and dirt. They filter things you don’t want inside your swamp cooler.

As long as the air filter in your swamp cooler is dry, bacteria and dust will just accumulate, but they won’t grow.

As soon as you add water, life explodes. New bacteria grow and worsen the smell of your swamp cooler.

The worst mistake you can do is to rinse an air filter with water and replace it without drying.

That happened to me once and I had to dispose of the air filter afterwards. Even though it looked clean, it smelled so badly that it was impossible to use.

So, just dry off any visible dust using a dry brush!

Rinse air filters with water

Only ever rinse your air filters with water if you can put them outside in direct sunshine until they are fully dry.

I still recommend dry-brushing over rinsing air filters …

Clean the water tank

The next step is to clean the water tank. The water tank can collect algae and bacteria over time.

You can tell if the water tank visibly discolors. I’ve seen water tanks that had a slimy green coating on the inside.

Before you clean the water tank, you first have to drain it. To do that, either place a drain pan below your swamp cooler or move the entire swamp cooler outdoors.

Then, open the drain hose.

After that, close the drain again and fill the tank with half water, and half distilled vinegar (as strong as possible).

Let that sit for an hour.

Afterward, drain again. Ideally, scrub the inside walls of the water tank. If you can’t reach the inside, you can use a pipe cleaner brush like this one (click to view it on amazon).

Then, refill the tank with fresh water.

3. Clean the water hose

If you use your swamp cooler with a water hose (for continuous refills), some of the smell inside it can come from the bacteria and algae from the water hose.

So, if you want to clean everything perfectly, you should clean the water hose as well.

The water hose, is, however, rarely the problem.

So, I recommend you only clean the water hose if you already cleaned everything else and your swamp cooler still smells after a couple of days of usage.

To clean a water hose:

Put the hose in a big bucket of water. Pour in a cup of vinegar or half a cup of bleach.

Let the hose sit in the solution for 24 hours.

After that, rinse the hose with water. And, of course, run water through the hose to get the vinegar or bleach solution and all the dissolved dirt out.

4. Clean the exterior

When cleaning your swamp cooler, don’t forget about the exterior. Especially the fins covering the water pads can hold a lot of dust.

You can wipe the entire swamp cooler’s surface with a wet cleaning cloth. Or you can just dust off the debris from the swamp cooler’s surface.

I like to use a vacuum for that. Of course, the standard carpet attachment doesn’t work well for that. I like to use an attachment intended for narrow spaces such as couch slits or cars.

vacuum cleaner attachments for cleaning

Once that’s done, your swamp cooler is ready to run again! The smell is gone now.

How to avoid swamp cooler smell in the future

The smell in swamp coolers always comes from bacteria, which, in turn, come from the dust accumulating in and around the swamp cooler.

So, to avoid the smell, you have to minimize the dust exposure of your swamp cooler.

There are two approaches to minimizing dust exposure. And you should take both of them:

1. Regularly remove dust from your swamp cooler

The first approach is to regularly clean your swamp cooler. If you regularly clean your swamp cooler, it is impossible for bacteria colonies to grow quickly.

Bacteria grows exponentially. That means the size of a bacteria colony doubles every couple of hours or days (depending on the species).

If your entire swamp cooler houses a colony of 100 bacteria cells, and the colony size doubles after a day, that’s 200 bacteria cells afterward. So, in a day, your swamp cooler accumulates 100 new bacteria.

However, if your swamp cooler houses 1,000,000 (a million) bacteria, within a day the growth rate will be another million cells. That’s where you truly notice exponential growth.

Your job is to regularly rinse the water pads and dust your swamp cooler to reduce the bacteria colony inside to sizes with small daily growth rates.

And the frequency of your cleaning derives from the growth rate of bacteria, e.g. rinse the pads every week or two.

2. Don’t even allow dust to enter your swamp cooler

Additionally, when you don’t use your swamp cooler, don’t keep it open for dust and dirt to enter.

Sometimes, even insects such as wasps will enter swamp coolers, carry debris inside and build a nest.

Dust, dirt, and insects are not welcome.

You can keep them out using this Hessaire swamp cooler cover (click here to view it on amazon).

That’s a simple cover you can put on your swamp cooler whenever you don’t use it.

It keeps dirt, dust, and insects out. And if you use your swamp cooler outdoors, it prevents the swamp cooler discovering from the sun’s UV rays.


You can clean your swamp cooler by rinsing the water pads regularly. To clean the water tank, fill it with distilled vinegar and water. Let it sit and then use a pipe brush to clean out all the dirt.