Continuous Positive Airway Pressure (CPAP) therapy is a standard treatment for obstructive sleep apnea, delivering pressurized air to keep airways open during sleep. Many modern CPAP machines include an integrated heated humidifier, which adds moisture to the air stream to prevent dryness and irritation in the nose, mouth, and throat. This feature improves comfort and compliance for users, leading to questions about maintaining the water reservoir.
Daily Water Replacement: The Core Recommendation
The answer to whether the water must be changed daily is a clear yes, according to device manufacturers and medical professionals. The primary reason for this daily change is to maintain a hygienic environment within the water chamber and the entire air delivery system. Water that remains in the CPAP reservoir for more than 24 hours quickly becomes stagnant, creating an ideal environment for microbial growth.
The combination of standing water, warmth from the heating plate, and moisture from your breath creates a breeding ground for bacteria, mold, and other pathogens. These microorganisms can rapidly multiply and be aerosolized, meaning they are blown directly into your airways and lungs during therapy. This contamination risk can lead to respiratory issues or sinus infections.
To mitigate this risk, discard any water remaining in the chamber immediately upon waking, even if it appears clean or almost full. Simply topping off the reservoir is insufficient, as it leaves behind concentrated microbes from the previous night. After emptying the tank, rinse it briefly with clean water and allow it to air dry completely throughout the day. This discourages the growth of any remaining organisms and ensures you begin each night with a fresh, clean supply of water.
Why Water Quality Matters
Beyond the frequency of replacement, the specific type of water used in the CPAP humidifier is important for both your health and the longevity of the machine. Manufacturers strongly recommend using only distilled water in the reservoir. Distilled water is created by boiling water into steam and condensing it back into a liquid, a process that effectively removes all dissolved minerals, chemicals, and microbial contaminants.
Tap water contains various minerals, such as calcium, magnesium, and iron, and often has chemical additives like chlorine or fluoride. When tap water is heated by the CPAP machine’s heating element, the water evaporates, but these dissolved solids are left behind. Over time, these residual minerals precipitate out of the solution, forming hard, white deposits known as scale or mineral buildup on the walls of the water chamber and the heating plate.
This mineral buildup can negatively affect the machine’s performance, reducing the efficiency of the humidification system. The scale acts as an insulator, preventing the heating plate from effectively transferring heat to the water, which reduces the amount of moisture delivered into the air. If the buildup becomes severe, it can damage the reservoir and the heating element, potentially shortening the lifespan of the CPAP device. Using mineral-free distilled water prevents this scaling, ensuring consistent humidification and protecting the machine’s components.
Essential Weekly Humidifier Maintenance
While daily water changes address immediate hygiene, the CPAP water reservoir requires a deeper, more thorough cleaning once a week to remove any bio-film or mineral residue that may have accumulated. This weekly regimen involves physically washing the chamber components to ensure complete sanitation. The first step is to disassemble the water chamber completely, separating any removable parts according to the device’s manual.
Next, wash all parts of the reservoir using warm water and a mild dish soap. Ensure the detergent is unscented, non-moisturizing, and free of harsh chemicals like bleach or alcohol. Gently scrub the interior surfaces to remove any slick bio-film that can harbor bacteria. For deeper cleaning, soak the reservoir in a solution of one part white vinegar to three or four parts water for 15 to 30 minutes, which is effective at dissolving minor mineral deposits.
After washing or soaking, a thorough rinse under clean, running water is necessary to remove all traces of soap or vinegar residue, which could be irritating if inhaled. The final step is to allow the reservoir to air dry completely before reassembly. Placing the components on a clean towel, away from direct sunlight, ensures that no moisture remains in hidden crevices, preventing the formation of mold or mildew.