The continuous positive airway pressure (CPAP) machine is a standard treatment for sleep apnea, and many models include a heated humidifier to prevent airway dryness. This humidifier gently warms water to add moisture to the pressurized air, making therapy more comfortable and preventing side effects like nasal irritation or congestion. Because the humidifier creates a warm, moist environment, which is ideal for microbial growth, the water in the CPAP reservoir should be emptied and replaced every single day to maintain hygiene.
The Necessity of Daily Water Replacement
The primary reason for daily water replacement is to prevent the growth and aerosolization of harmful microorganisms. Stagnant water, even after a single night, provides a breeding ground for bacteria, mold, and fungi. When the CPAP machine is used, the humidifier heats this water, and any contaminants present can become airborne and inhaled directly into the user’s respiratory system.
Leaving water in the chamber increases the risk of breathing in contaminants, potentially leading to respiratory infections. The respiratory tract is vulnerable to inhaled germs. Even if the water level is low, remaining water should be discarded, and the chamber rinsed and air-dried during the day to deprive microbes of moisture.
The amount of water used varies based on the machine’s settings, climate, and sleep duration. Regardless of how much water is left, the warm, moist conditions rapidly promote the development of biofilms and microbial colonies. Emptying the reservoir daily ensures the water you breathe each night is fresh and clean, significantly reducing the risk of introducing pathogens.
Why Water Quality Matters for Humidifier Health
Distilled water is the only recommended option for the CPAP humidifier, as it has been processed to remove minerals and impurities. Using tap water, which contains natural minerals like calcium and magnesium, introduces the risk of developing scale deposits inside the water chamber.
When tap water is heated, minerals precipitate out and form scale buildup. This accumulation reduces the humidification system’s efficiency by insulating the heating element, decreasing the moisture added to the air. Over time, this buildup can damage the CPAP equipment and shorten its lifespan.
Beyond damaging the equipment, mineral deposits and contaminants like chlorine can pose health risks. The residue creates microscopic crevices where bacteria and fungi can attach and grow, compromising chamber hygiene. Using distilled water eliminates these risks, ensuring the CPAP unit operates optimally and minimizes the inhalation of particles or irritants.
Essential Weekly Cleaning of the Water Reservoir
While daily water replacement addresses immediate hygiene, a deeper weekly cleaning is necessary to remove invisible biofilms and spores adhering to the surfaces. Daily dumping and refilling are insufficient to fully sanitize the chamber, as the warm, moist environment fosters resilient microorganism growth. A weekly sanitation routine prevents biological residue from accumulating and compromising respiratory health.
For the weekly deep clean, the reservoir should be disassembled and washed thoroughly with warm water and mild, unscented dish soap. Avoid using harsh chemicals or antibacterial soaps, as they can damage the material or leave irritating residues. Alternatively, a dilute white vinegar solution provides an effective sanitizing soak to break down mineral buildup and microbial films.
The vinegar solution is commonly recommended at a ratio of one part white vinegar to three or nine parts water, soaking the chamber for 15 to 30 minutes. After soaking or washing, the reservoir must be rinsed completely, ideally using distilled water for the final rinse, to ensure no residue remains. Finally, allow the reservoir to air dry fully on a clean towel before reassembly, as residual moisture encourages the regrowth of mold and bacteria.