For a brief but thorough introduction to heated, passive (unheated), integrated (built-in), and stand-alone humidifiers, see Answers, Humidifiers at https://www.cpap.com/cpap-faq/Humidifiers.html#FGID-61. When you try unheated humidification, you may find that it does little to keep your nasal passages open and isn’t comfortable, unlike heated humidification. Since a heated humidifier can be turned off and become a passive humidifier, it may make sense to get a heated humidifier for more options. To keep humidity levels high, use an Australian heated hose from http://www.sleepzone.com.au/ CPAP users find that they need to use the heated humidifier every night, even in warm, humid summer months and humid climates. To preheat the water, turn on the humidifier about 20 minutes before going to bed. Some users recommend having a spare tank, since the cost is only about $20 or less; see https://www.cpap.com/simple-find-cpap-products.php?selected=HUMIDIFIERPARTS
People may have memories of unsanitary, portable room humidifiers and vaporizers heavy with mineral deposits, growing and spreading bacteria. CPAP humidifiers are different if you use clean distilled water, emptied daily or frequently. Use only distilled water in the humidifier to avoid mineral buildup. Distilled water is condensed steam, mineral free, sold in gallon bottles for usually less than $1 at grocery stores and WalMart, for use in humidifiers and steam irons. If you are traveling or run out of distilled water, it’s okay to use tap water for a few days, but your humidifier may show mineral deposits. To remove deposits, soak the tank in a mild white household vinegar solution and rinse well. Since bacteria, molds, and mildew won’t grow on a dry surface, empty the tank every morning for best results and remove the bottom plate (in a Respironics humidifier) and let it air dry. For tips on taking apart and assembling a humidifier, see the discussion thread http://www.cpaptalk.com/viewtopic.php?t=10305
After drying, replace the humidifier on the machine. See a discussion of humidifier water leaks at http://www.cpaptalk.com/viewtopic/t14183/Puddle-Underneath-CPAP-Unit.html and search cpaptalk.com for discussions on the leaks related to the integrated humidifier for the Respironics M series PAP. Make sure the humidifier connects snuggly to the machine, to avoid air leaks. To fill, use a funnel in the opening for the hose (with the hose removed). Store the distilled water in the bedroom. For ideas on filling the humidifier, see http://www.cpaptalk.com/viewtopic.php?t=13397 To save wear and tear on the end of the hose, use a hard plastic hose connector.
Some people don’t empty the tank daily and have no problems with things growing in the humidifier. If you don’t empty the tank, consider removing or disconnecting the humidifier from the PAP machine so the inside of the machine can dry out during the day, to avoid growth of mildew inside the machine.
Don’t add anything to the clean distilled water. The air that passes over it goes directly into your lungs. It’s not aroma therapy, it’s CPAP respiratory therapy.
To protect furniture, keep the heated humidifier and machine on a waterproof surface in case you spill water or there is a leak. Some options are an inverted plastic lid from a large storage box, or a cookie sheet with a rim.
Experiment with the various humidifier settings to find the best setting for you. Also briefly experiment with passive humidification (don’t turn on the heating element) in case you ever need to run the CPAP on battery power during a power outage or when camping, since heated humidifiers can’t be run on batteries unless you use an inverter. Once you find an optimal heat setting, notice how much water is required nightly, and fill the tank only to that level, if you want to avoid wasting water with daily emptying. Don’t fill beyond the fill line, since overfilling may interfere with correct machine operation.