Cleaning your CPAP reservoir takes about five minutes a day and a 20- to 30-minute soak once a week. The daily routine is simple: empty leftover water each morning, wash the chamber with warm soapy water, rinse it, and let it air dry. A weekly deeper clean with vinegar or soapy water kills bacteria and dissolves mineral buildup before it becomes a problem.
Why a Clean Reservoir Matters
Warm, standing water is an ideal environment for bacteria and mold. If those organisms grow inside your humidifier chamber, your CPAP pushes them directly into your airway while you sleep. That can trigger illness or worsen existing conditions like asthma or reactive airway disease. A consistent cleaning routine keeps the reservoir safe to use and extends the life of the chamber itself.
Daily Cleaning Steps
Every morning, unplug your CPAP and detach the water chamber. Pour out any remaining distilled water from the night before. Then wash the chamber with warm water and a mild dish soap (something like Ivory liquid works well). You can lather the inside with your hands or fill the chamber with soapy water and gently shake it to reach all interior surfaces.
Rinse thoroughly with warm water so no soap residue remains. Pat the chamber dry with a clean towel, then leave it open on a flat surface to finish air drying. Keep it out of direct sunlight, which can degrade the plastic over time.
Weekly Deep Clean
Once a week, give the reservoir a longer soak to disinfect it and break down any film or residue that daily washing misses. You have two good options for the soaking solution:
- White vinegar solution: Mix 2 parts white vinegar with 3 parts water (roughly 1 cup vinegar to 1½ cups water). Some sources recommend equal parts vinegar and water or a 1:3 ratio. Any of these concentrations will work for disinfection and mineral removal.
- Warm soapy water: Fill the chamber with warm water and mild dish soap if you prefer to skip vinegar.
Let the chamber soak for 20 to 30 minutes. If you notice white mineral scale on the interior walls, a soft-bristled brush or long narrow brush helps scrub it away while the chamber is soaking. After the soak, empty the solution, rinse well with warm water, dry with a clean towel, and air dry completely before reassembling.
Removing Mineral Buildup
White, chalky deposits inside the reservoir are mineral scale, usually calcium and magnesium left behind when water evaporates. Vinegar is the most effective household solution for dissolving these deposits. Soak the chamber in a 1:3 mixture of white vinegar and warm water and use a brush to loosen stubborn spots on the interior walls. Rinse thoroughly afterward to eliminate any vinegar smell.
The best way to prevent mineral buildup in the first place is to use distilled water. Tap water contains minerals that cause scaling, and even boiling it only kills bacteria without removing the mineral content. Tap water can also contain chlorine and fluoride, which may irritate your airways or damage the chamber over time. Distilled water is free of minerals and bacteria, which is why manufacturers and sleep clinics consistently recommend it.
Drying the Right Way
Proper drying is just as important as washing. A damp reservoir sitting in a closed space invites mold growth between uses. After washing, pat the chamber with a clean towel and then leave it open on a flat, clean surface. Position it so air circulates through the opening. Avoid placing it in direct sunlight or near a heat source, as UV exposure and high temperatures can warp or degrade the plastic.
On mornings when you skip a full wash, still empty the leftover water and leave the chamber open to dry. This alone discourages bacterial growth between deeper cleanings.
What Not to Use
Stick to mild dish soap and white vinegar. Harsh chemicals, scented cleaners, and antibacterial soaps can leave residues that you’ll inhale during the night or damage the chamber material. Bleach solutions and alcohol disinfectants are listed by ResMed for wiping down the exterior of the machine itself, but they’re not meant for the water chamber that produces the moisture you breathe.
UV light cleaning devices marketed for CPAP equipment are another thing to skip. The FDA has warned that UV light may not reach interior surfaces of CPAP components, meaning germs can survive the process. Hand washing with soap or vinegar remains the recommended method.
Can You Use a Dishwasher?
Some manufacturers, including ResMed, allow dishwasher cleaning for the humidifier tub with specific restrictions: top rack only, and the water temperature must stay below about 130°F (55°C). However, ResMed also cautions that dishwashers can deteriorate CPAP parts and lead to earlier replacement. If your dishwasher runs hot or you’re unsure about the temperature settings, hand washing is the safer choice. Never put CPAP tubing in a dishwasher or washing machine.
When to Replace the Reservoir
Even with perfect cleaning habits, the humidifier chamber wears out. The standard recommendation is to replace it every six months. Over time, the plastic can develop micro-scratches and clouding that harbor bacteria even after washing. If you notice persistent discoloration, a lingering odor that doesn’t resolve with vinegar soaking, or visible cracks, replace the chamber sooner. Check your manufacturer’s guidelines, as replacement intervals can vary slightly by model.