How often to replace CPAP filters

The short answer

Most CPAP machines use one of two kinds of air filter, and they follow different rules:

Filter type	What it looks like	Medicare allowance	Typical care
Disposable (fine, ultra-fine, hypoallergenic)	White or light-colored paper-like fiber	2 per month	Do not wash; replace when grey or every 2 to 4 weeks
Reusable (foam, pollen)	Grey, black or blue foam	1 per 6 months	Rinse regularly, dry fully, replace about every 6 months

The Medicare figures come from the CMS replacement schedule summarized by the Sleep Foundation and used by suppliers such as Lincare. They are the maximum your insurance will typically pay for, not a medical rule.

Which filter does your machine have?

Open the filter cover, usually on the back or side of the machine where room air is pulled in. Some machines use a single disposable filter; others combine a reusable pollen filter with a thinner disposable one behind it. If you have both, they are on different schedules: the disposable one is swapped frequently, the reusable one is rinsed and kept for months.

Manufacturer guidance can be longer than the Medicare allowance. ResMed's product page for the AirSense 11 filters, for instance, says to check the air filter and replace it every six months, and sooner if it has holes or is clogged with dirt or dust. Philips lists its reusable pollen filter as "replace every 6 months". Fisher & Paykel suggests every 3 months for its device filters, or after significant discoloration or around 1000 hours of use. In other words, there is no single universal number; the schedule depends on the machine and on your room.

Why the room matters more than the calendar

A filter's job is to catch what is in the air before it reaches your lungs and the motor. The same filter can stay white for a month in a clean bedroom and turn grey in a week if you have:

• dogs or cats, especially if they sleep in the room;
• carpet, an open window near a road, construction nearby or a dusty climate;
• smoking in the home, or wildfire smoke outside;
• seasonal pollen allergies;
• a machine sitting on the floor rather than a nightstand.

In those conditions, treat two weeks as the real interval for disposable filters and check them every few days.

How to tell a filter needs replacing

1. Color. A new disposable filter is white. Hold it next to a fresh one or a sheet of white paper; if it looks grey or yellow, replace it.
2. Holes or tears. Any damage means unfiltered air is getting through.
3. A reusable filter that no longer rinses clean, crumbles, or has lost its springiness.
4. Changes in the machine. A louder motor or an unusual smell can mean restricted airflow.

Lincare recommends checking filters weekly. It takes a few seconds and catches the dusty weeks the calendar does not know about.

Can you wash a disposable CPAP filter?

No. Disposable filters are made of fibers that lose their structure when wet, and a damp filter can grow mold or let moisture into the machine. Replace it instead. Only foam or pollen filters marked as reusable should be rinsed, and they must be completely dry before you put them back.

How to clean a reusable filter

1. Unplug the machine and remove the filter.
2. Rinse it under lukewarm running water. Mild soap is fine if your manual allows it; avoid bleach and scented cleaners.
3. Squeeze out the water gently without twisting.
4. Let it air dry completely on a clean towel, out of direct sunlight.
5. Reinstall it, along with a fresh disposable filter if your machine uses one.

How often to rinse varies by source: some suppliers say weekly, the Sleep Foundation says every two weeks. Weekly is a safe habit if your room is dusty.

Filters and your insurance allowance

Because disposable filters are covered at two per month, many suppliers ship them in packs of six or more with each quarterly order. That is convenient, but it also makes it easy to forget to actually swap them: the pack sits in a drawer while the old filter turns grey. A few habits help:

• Change the disposable filter on the same day you change a nasal cushion. Both run on a two-week clock under Medicare, so one routine covers both.
• Keep the spare filters next to the machine, not in a closet.
• When you open the last filter in a pack, that is your signal to reorder, not when the slot is already empty.
• If you use a reusable foam filter, note the date you put it in. Six months is long enough that nobody remembers it.

What happens if you never change it

A clogged filter does not stop the CPAP from running, which is why it is easy to forget. But the motor has to work harder to pull air through, more fine dust can reach the tubing and the humidifier, and you may be breathing air that is less clean than your bedroom. Filters are also the cheapest part of the whole setup, so they are the easiest place not to cut corners.

Remembering it without thinking about it

The real difficulty is that a two-week filter cycle is easy to lose track of. Nightkit tracks the disposable filter on the free tier, together with the cushion and tubing, and reminds you a few days before it is due. With Pro it also tracks the reusable filter on its own six-month schedule and adds a weekly filter-rinse reminder to the cleaning schedule. You can shorten the interval if you live with pets or dust. Always follow your machine's manual and your equipment supplier when they disagree with a general guideline.