Humidifier accessories that are actually worth buying
Updated by Margot Sandoval. Three to buy with the machine, six that fix a specific annoyance, three for when you need a different appliance.
Quick answer
Humidifier filters and cartridges get all the attention, but three cheaper things turn a humidifier from a gadget into a working appliance: a hygrometer that is not inside the machine, brushes that reach the tank neck, and a descaler if your water is hard. After that it is situational: distilled water or a cartridge for white dust, the right lettered wick for evaporative models, and a tray if it is standing on wood.
What people worry about here
What is the white dust, and how do I stop it?
It is the dissolved minerals from your tap water, dried onto your furniture. The EPA's fact sheet says several studies have shown ultrasonic and impeller humidifiers disperse minerals from the tank into the air. You have three fixes: distilled water, a demineralization cartridge, or an evaporative humidifier, which leaves the minerals in its wick.
Ultrasonic and impeller units disperse mineralsUS EPA, Use and Care of Home Humidifiers
Filters, cartridges, wicks: what is the yearly cost?
Filter-free ultrasonic machines cost nothing to run except electricity and, if your water is hard, distilled water. Evaporative machines need a wick, and the letter matters: Honeywell's filters are A, C, D, E and T and they are not interchangeable. Consumer Reports' stated reason for recommending the Honeywell HUL430B is that it has no wick, cartridge or filter to replace at all.
$0 to about $40 a yearConsumer Reports; maker parts listings
Every third day, with the tank emptied and wiped every day it is in use. That is not a brand's upsell, it is the EPA's recommendation, and the reason is that standing water grows microorganisms and ultrasonic units are efficient at spraying them into the room. Empty, scrub off any film or scale, wipe dry, refill.
Every third dayUS EPA, Use and Care of Home Humidifiers
A hygrometer, brushes and a descaler turn the EPA's cleaning advice into something you will actually do.
A hygrometer that is not inside the humidifier
SMARTRO SC42 digital hygrometer
Every piece of advice on this site is a number between 30 and 50 percent. Without a second thermometer-hygrometer about three feet from the machine, you are trusting a sensor that sits in the wettest air in the room.
What to look for: A stated accuracy figure, and a display you can read from the bed.
White dust, a damp nightstand, the wrong filter, a machine sitting on the floor.
Distilled water, if your water is hard
Distilled water by the gallon
The EPA's advice for ultrasonic and impeller humidifiers is water with low mineral content, because those designs spray whatever is dissolved in the tank into the room.
What to look for: The label has to say distilled. Purified, spring and filtered are not the same thing.
Consumer Reports advises putting a humidifier on a flat surface raised at least two feet off the floor, so the moisture disperses instead of soaking the carpet.
What to look for: At least two feet tall, stable, and a surface you do not mind getting damp.
The useful question is not what the humidity is now, it is what it did at 4 a.m. while you slept. A logging sensor answers that once and then you can stop thinking about it.
What to look for: App history, not just a live number.
People search for both in the same week, so it is worth saying plainly: a purifier removes particles, a humidifier adds water. Neither does the other's job.
What to look for: Match the CADR to the room; a purifier does not change humidity at all.
Minerals from your tap water. The EPA says ultrasonic and impeller humidifiers disperse minerals from the tank into the air. Switch to distilled water, fit a demineralization cartridge, or move to an evaporative humidifier, which leaves the minerals in its wick.
Do I need distilled water in a humidifier?
If you have hard water and an ultrasonic humidifier, yes, or a demineralization cartridge instead. The EPA recommends water with low mineral content for ultrasonic and impeller units. Evaporative and steam units are far less fussy.
Is a filter-free humidifier better?
Cheaper to run, not cleaner. Filter-free means ultrasonic, which is the design the EPA singles out for dispersing minerals and microorganisms from the tank. A wick costs money and captures minerals. Consumer Reports does recommend one filter-free model, the Honeywell HUL430B, specifically because nothing needs replacing.
How often should I clean a humidifier?
Every third day, and empty and dry the tank every day you use it. That is EPA guidance, not a maker's recommendation. Scrub off scale and film, wipe dry, and rinse thoroughly if you used anything other than water.
Do I need an air purifier or a humidifier?
They solve different problems. A purifier removes particles from the air and changes the humidity not at all. A humidifier adds water and filters nothing. If your complaint is dust or allergens, buy the purifier; if it is a dry throat and cracked lips, buy the humidifier.
Humidifier or dehumidifier for a damp bedroom?
Measure first. Below 30 percent, humidify. Above 60 percent, dehumidify. The CDC's mold advice is to keep household humidity no higher than 50 percent, so a damp bedroom is a dehumidifier problem even though it feels like an air problem.