one of our members, Dan Levy, posted this on another thread. I'm breaking it out in this separate thread so that more people see it:

"The cleaning routine I recommend is:

1) On a daily basis, rinse out the humidifier daily with regular tap water, and clean the nasal cushion or pillows with soap and water. Don't use antibacterial soap or soap with skin softening agents as these will affect the medical grade silicone.

2) On a weekly basis, thoroughly soak and rinse the humidifier chamber, the tube, and all the parts of the mask except the headgear. Use a mild soap like Ivory or Joy dishwashing liquid, as long as it is not the antibacterial kind.

3) On a monthly basis, after you've done the weekly routine, soak everything you clean weekly in a solution of one part distilled white vinegar to ten parts water. That's strong enough to kill any mold, mildew, or other nastiness, yet weak enough that it won't harm your lungs. After soaking about 20 minutes, rinse everything very thoroughly with water. Also on a monthly basis, check your filters. Wash out reusable filters, and replace disposable filters if they are visibly dirty.

Not too onerous. Some clean freaks do the weekly routine on a daily basis and the monthly routine on a weekly basis. No harm, but its more work than is usually necessary."