Carry your tank to the sink. Flip it upside down and unscrew the cap. Fill it with cool water—never hot, because steam could warp the plastic. Leave a little air at the top, about an inch. This helps the water flow smoothly when you reattach it.
If your tank has a handle, use it. If not, cradle it like a sleepy cat. You are a gentle, powerful being. Screw the cap back on tightly, then flip it right-side up. Hear that slosh? That’s the sound of victory.
Pro tip: The “listen and tilt” trick
When you seat the tank back onto the base, you might hear a gurgle. That’s the water rushing in—a happy little burp. If you don’t hear it, just tilt the tank slightly to break the seal. Problem solved in two seconds.
Plug your humidifier back in. Set it to your desired mist level. Now step back and admire your work. You just gave your air a drink. How often do you get to say that?
How To Fill Ultrasonic Humidifier [Quickly And Easily] - HVACseer.com