A humidifier that’s switched on but producing little or no mist has a short list of common, checkable causes before assuming a fault.
Scale buildup on ultrasonic models
On an ultrasonic humidifier like the Dreo DR-HHM006, mineral scale on the small vibrating disc is a common cause of reduced or absent mist output — see our descaling guide for the fix.
Check the tank is properly seated
A tank not fully seated on the base can prevent the unit from reading water level correctly, causing it to behave as if empty even when it isn’t. Remove and reseat the tank fully.
A clogged wick, on evaporative models
The Philips HU2716/10 and similar evaporative humidifiers rely on a wick drawing water up to be evaporated by airflow — a wick that’s become clogged with mineral deposits reduces output and may need cleaning or replacement, following the manufacturer’s guidance.
Check the water level itself
An empty or nearly empty tank is the simplest cause of all, and easy to overlook if the tank appears to have some water but not enough to cover the intake properly — top it up fully and check again.
What we would not do
Assume a lack of mist means the motor or ultrasonic element has failed before checking scale buildup, tank seating and water level — the three most common, and most easily fixed, causes across this family.
The questions that keep coming up
Could the water level sensor be at fault?
It's possible, but check the simpler causes first — an improperly seated tank not making contact with the base, or a tank that reads as empty due to a small amount of water not covering the sensor properly, are both more common and easier to fix than an actual sensor fault.
Last reviewed 24 August 2026