Desktop Humidifier





Introduction: Desktop Humidifier

About: I'm a jack of all trades and a master of none. I like to tweak, mod and improvise whenever possible!

Every winter its the same thing. Temperatures drop, the air gets dry and noses start running away. One thing that helps is having a good humidifier in your home. But hat about your office at work? Most humidifiers i see are pretty big and would take up too much desk space. Not to mention can be overkill for a small office. I for one sit in a little 10'x10' office. So i need a decent humidifier that is no bigger then an adult shoe box. Having found nothing that size commercially i had to come up with something on my own. Here is what i came up with. 

Materials Needed:

- Empty baby wipes container
- Scrap piece of aluminum (approximately 7.5"x5")
- 20oz Dasani water bottle
- 80mm PC fan with mounting screws
- SPDT switch (any switch will do)
- 9V AC/DC power adapter 
- power connector compatible with your AC/DC power adapter
- Humidifier filter
- Small peice of scrap wire ( approximately 6")

Tools Needed:

- Dremel with fiberglass reinforced cutting wheel. 
- Cordless drill
- 1/4" drill bit
- 5/32" drill bit
- jewelers file set
- Tin snips
- Hot glue gun
- Phillips head screw driver
- Soldering iron
- Scissors


- Laying out the Container
- Fitting the top plate
- Adapt the bottle
- Wire the electronics
- Final product

Step 1: Laying Out the Container

For the container we will be using an empty baby wipe container. The top of the container is rounded and makes it very difficult to mount anything to it. Rather then remove the top completely we want to hold onto it for easy access to the inside for cleaning and changing of the filter. Using our Dremel with cut off wheel we want to cut out a 6.25"x 4.5" section from the top of the container. Leave about 1/4" of material along the back side of the container. This will put you in line with the back side of the flip up lid's hinge joint. 

Next we need to make a couple of 1/4" cuts into the front part of the lid. The area where the flip lid release button use to be. This is where the top plate will be fitted and helps hold it in place.

Along the left side of the container we need to create a vent. This is where the air will be drawn through the filter collecting the moisture. The plan is for the bottle to be on the left side of the container. First you want to measure about 1.5" up from the bottom then start drilling 1/4" holes into the side. The more holes you put in the better airflow you will have across the filter. I did 4 rows of 7 holes.

Don't forget to use your files or even some sand paper to clean up the cut and drilled edges.

Step 2: Fitting the Top Plate

Now we want to lay out the top and decide where we want thing. When looking at the front of the container we want the bottle to be on the same side as the vent. The water bottle that will feed the humidifier will sit right next to the exhaust fan. So we lay out 2.75" diameter holes onto the plate .75" from the edges. Which should leave about .5" between the 2 holes. We also want to lay out the power switch. Please note that all marking and cutting will be done on the reverse side of he plate so that any time the Dremel runs from us it is not marring up the side that will be visible. So keep track of which side is the bottle side. This side needs more attention while cutting to ensure a good fit around the bottle.

To cut the holes we use a Dremel with cut off wheel. We want to stay just inside our lines while cutting. We will use the file set to finish off the cut. A grinding wheel for the Dremel can also be used to finish off the cuts. It is best to use the file set on the bottle hole to ensure you get a good fit around the bottle. We need to file to our marks and test fit the bottle to see if we need to remove more materiel.  To cut the hole for the switch use a 1/4" drill bit to drill out the center then the files to finish off the hole. Be sure to do a good job of rounding off the edges of the bottle hole to prevent damage to the bottle. Feel free to make the hole wide enough to fit a gasket around the hole to better protect the bottle and create a better seal. Though there may not be enough room for that.

Next we measure for the fan mounting holes. The easiest way to do this is to center the fan over the hole and mark 2 mounting holes diagonally from each other. It takes a 5/32" drill bit to drill the mounting holes. Now using the tin snips we want to round off the corners of the plate and get it fitted into the top of the container. Fit the back side of the plate into the slots we cut in the front of the container. Check the fit, you may need to remove some more material to get the plate to sit flat without stretching the lid. You may even need to increase the depth of the slots.

To finish this up we will fill in all the gaps around the plate with a good helping of hot glue. This not only helps to hold the plat in place but also prevents air flowing through the gaps. Don't fill in the large gap in the front face. This is where you will be putting the power plug and will ultimately be the back side of the finished product. 

Now would be a good time to paint this the color of our choice. Be sure to tape off all the holes from the inside so no over spray gets in there.

Step 3: Adapting the Bottle

This is very straight forward. In the unit the bottle will bottom out. So we need to modify it a bit to allow the water to flow and fill only the bottom 1/4" of the container. This is all that is needed to allow the filter to soak up the water and disperse it into the air. First we need to remove the cap and the ring the cap sucured to when the bottle was new and unopened. Using our Dremel and cut off wheel again we cut 4x 1/4" wide 1/2" deep chunks out of the lip of the bottle. Clean up the cut edges with the file and your ready to move on.

Step 4: Wire It Up

Now we want to wire it up and mount the electronics. We want to placed the switch into its hole and mount the fan to the under side of its hole. Place a couple dabs of hold glue around the bottom side of the switch to help hold it to the plate. We will want to keep the power plug out of its hole to make it easier to solder. 

All we need is some basic soldering skills to put this together. Solder the negative lead of the fan to the negative lead of the power connector. Now we solder our spare bit of wire to the positive lead of the power connector. Solder the positive lead of the fan to the switch. Now take the other end of the scrap peice of wire and solder it to the switch. Now place the power plug in its hole and fill the hole with hot glue. It would be a good idea to cover all exposed conections while we are at it. 

We can easily add an LED to the circuit so you have a power indicator but the noise from the fan should be enough. Just be sure to use the right resistor with the LED since this device can use 9V or more. 

Step 5: Final Product

All that's left to do is cut the humidifier filter to size and put it in place. Any house hold scissors should do the trick. There is no need for any kind of bracket to hold the filter in place. The water bottle does that for you. Just cut a piece of filter to 3.5"x4" and place it against the vent side of the container. Secure the lid and your ready to add water. We can now fill up our 20oz boddle and quickly dump it upside down into the unit. The bottom 1/4" of the container will fill with water. Plug the 9V AC/DC power adapter into the back and flip on the switch. Now we can enjoy the nice cool humidity.

How it works:
Water sitting in the bottom of the container is soaked up by the filer. The fan draws air in through the vents and across the filter picking up moisture. The nice moist air is then blown out through the top by the fan. As the water is dispersed into the air the bottle feeds more water into the container ready for dispersal. 

The unit takes 8 or 9 hours to run through a full 20oz bottle of water. Depending on how good of a fan you use. Making it perfect for use in the office. Just remember to replace the filter every month or when more then just the top edge of the filter turns brown. Its a good idea to leave the unit running for a while after the water runs out to allow the filter to dry. This helps prevent mold buildup on the filter. 

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Nice!!... Thanks for sharing this project, mpilchfamily.

I'm building this for a (slightly) different purpose than yours... To humidify a self-build egg incubator... Inside the incubator (small enclosed space), precise % of humidity is required, so I thought: Why not replace the simple on/off switch, for a humidity relay switch?... Something like this:

As anyone tried this?... The "chalenge" is to find out if I can get the humidity % precision I need, with this switch.

Anyway, as for the humidifier unit itself, thanks again mpilchfamily... Great project!... I'm definitely building it!... With the relay/switch.



Hi, from what I gather you have the fan sucking air into the tray and blowing the damp air out through the fan. The fan will not last long, moisture inside the fan will corrode and destroy the control PCB inside the fan.

Better to blow air into the tray through the fan, better to move the fan away from over the tray to the inlet near the damp filter, I like the concept all recyclable materials.


1 reply

The fan doesn't get more than about 60% humidity running through it. About what you would have on any average spring day along the central east coast of the States. More than you get on a winters day but well less than most larger humidifiers can do. I've been running this setup for just over 2 years now without any problems from the fan. Besides the fan is pulled from an old PC anyway. So it's done it's job up till now. Easy to get a replacment for next to nothing too.

Thanks for checking the project out.

Hi, this is really awesome! Why, though, do you need a bottle to disperse water? would it work as well if I just drill the vent holes a little higher and fill with water until there? also, if I put the vent holes in the lid, opposite the fan, and separate them with filter, would it work? thanks!

1 reply

Sure you can put the vent holes higher and put more water in the bottom but it won't last as long. A 20oz bottle feeds the unit for about 8 hours. A couple of inches of water in the bottom isn't anywhere close to 20 oz of water.

The filter has to sit in the water. The humidifier works cause the air picks up some moisture as it passes through the wet filter. Placing the filter in some sort of holder in the middle may work but it will be easy for the air to go around the filter rather than through it. The design used seems to work best. The fan draws air into the unit forcing it through the filter. Another benefit is any dust gets stuck in the filter and doesn't end up in your water. Your idea would result in dirty water and a mess to clean up on a regular basis.

I feel stupid for asking this but i don't understand how the water bottle disperses water

1 reply

The cut outs in the top of the bottle allow the water to flow out into the container. It will do so until the water level in the container gets just above the height of the cutouts. Self refilling pet water dishes and those large water coolers with the 5 gallon bottles sitting on top work the same way.

This might work more efficiently atop a board on a radiator, or near a source of heat, or a heat register.

1 reply

This is meant to be a cool mist humidifier. I own this humidifier and loosely based the build off it.

This is a great idea .I hope you dont mind I built one with a few mods, My daughter is sick and needed one and I saw this. It works great I made mine child friendly. Thanks for sharing.

1 reply

Glad it could help. I'd love to see what kinds of changes you made when you get a chance.

How would you get your computer wet. If your worried about it being to close to your PC its not a problem. Even in a little 10' x 10' room it only raises the humidity to about 30% at best. That's just a guess but it doesn't put that much moisture in the air. Like i said it takes about 8 or 9 hours for it to put 20oz of water into the air.

This is a great looking project.

I have a question. Why is the filter closer to the bottle than the fan?

3 replies

The fan sucks the air through the filter through the holes he drilled in the side of the container. This forces air through it instead of just going over it

Ahh... Thanks.

Plus the bottle helps to hold the filter against the side of the container.

Looks good. I want to build a bigger one for the bedroom. 2 fans and 2 liter soda bottle. I can get filters at Habitat for Humanity.

this is very neat. One question. in my experience using a bottle this way, the suction tended to collapse the botte. how have you solved thath problem here?

1 reply

There is a little bit of suction but not enough to overwhelm the bottle's integrity. No water is being sucked out of the bottle its all gravity fed. Just like any self feeding dog water dish or water cooler. Once the water level drops below the cut outs the bottles sucks in an air bubble allowing more water to fill the unit. In the past 2 weeks i haven't seen any part of the bottle collapse.