Continuous Positive Airway Pressure (CPAP) therapy is a common treatment for obstructive sleep apnea. Most modern CPAP devices feature an integrated humidifier, which adds moisture and warmth to the airflow, significantly improving comfort and promoting consistent use of the therapy. The quality of water used in this humidifier is a consideration for both the machine’s functionality and the user’s respiratory health.
Why Distilled Water is Required
Distilled water is the required choice for CPAP humidifiers because it is nearly pure, having been stripped of minerals and impurities. This purification process involves boiling water into steam, which leaves behind all dissolved solids. The steam is then condensed back into liquid, resulting in water virtually free of non-volatile substances like salts and minerals.
The primary reason for using this purified water is to prevent the accumulation of scale, or mineral deposits, within the humidifier chamber and on the heating plate. When mineral-containing water, such as tap water, is heated and evaporated, these solids are left behind as a chalky residue. Over time, this scale buildup obstructs the humidification mechanism, reducing efficiency and potentially causing premature equipment failure. Using distilled water ensures the heating element and water chamber remain clean, extending the machine’s lifespan.
Consequences of Using Impure Water
Using water sources other than distilled water, such as standard tap water or most bottled waters, introduces contaminants that pose risks to the CPAP machine and the user’s health. Tap water, even if safe for drinking, contains dissolved minerals, chemicals like chlorine, and trace metals. When these substances evaporate in the humidifier, they concentrate and form a hard, white film.
This mineral buildup reduces the heat transfer efficiency of the heating plate, causing the machine to work harder and potentially leading to malfunction or voiding the warranty. A more serious concern is the health risk associated with introducing pathogens into the system. Tap water is not sterile and can harbor microorganisms, including bacteria and fungi. When the humidifier heats and aerosolizes the water, any microbes present are delivered directly into the user’s airways and deep into the lungs. This can lead to serious respiratory infections, such as pneumonia. Even bottled water can contain enough dissolved solids to cause significant scaling and still carry a risk of microbial contamination when aerosolized.
Handling Water Tank Maintenance and Short-Term Needs
Consistent maintenance of the CPAP water tank is necessary to prevent the buildup of mineral scale and bio-film, which is where microorganisms thrive.
Daily Maintenance
Users should empty the humidifier chamber completely every morning and wipe it clean before allowing it to air-dry. Avoiding standing water in the tank is important, as this creates a moist, warm environment ideal for bacterial and mold growth. The chamber should be refilled with fresh distilled water immediately before use each night.
Weekly Cleaning
A weekly cleaning protocol should involve washing the water chamber with warm water and a mild, unscented soap. Some manufacturers suggest a weekly or monthly soak in a solution of two parts white vinegar to three parts water to dissolve any initial mineral deposits. This must be followed by a thorough rinse with clean water.
Emergency Use
If distilled water is temporarily unavailable, non-distilled options should only be used as a short-term substitution for one or two nights at most. In such an emergency, purified bottled water or tap water that has been boiled for several minutes and allowed to cool is the least detrimental option. However, using any non-distilled water necessitates an immediate and thorough cleaning of the water tank afterward to remove introduced minerals or contaminants. Tap water should never be used regularly, as the cumulative damage and health risks are substantial.