Continuous Positive Airway Pressure (CPAP) therapy uses pressurized air to keep the airway open during sleep. This often leads to dryness in the nose, mouth, and throat. To counteract this, most CPAP machines incorporate an integrated heated humidifier. This device adds moisture to the pressurized air stream, improving comfort and encouraging consistent use of the therapy. The humidifier requires a small reservoir of water to function throughout the night.
Typical Water Consumption Rates
CPAP humidifier usage is typically measured by how frequently the water reservoir needs refilling. Most standard water chambers hold between 300 and 400 milliliters of water, and under moderate use, a full tank is expected to last for one to two nights of continuous use. The actual rate of water consumption is determined by the machine’s internal mechanics, which heat the water to create the moisture vapor. When the humidifier is set to a higher output level, the heating element increases the water’s temperature, leading to a faster rate of evaporation. High humidity settings combined with long sleep duration can deplete a two-night reservoir in a single eight-hour session.
Factors Influencing Usage
The amount of water a CPAP humidifier consumes varies significantly based on environmental and user-defined settings. The most direct influence is the humidifier setting itself; a higher setting demands more water to be heated and evaporated into the air delivered to the mask. Users who prefer a high level of moisture to alleviate dryness will see their water tank empty faster.
The ambient conditions of the bedroom play a substantial role in determining consumption. In a cold room, the CPAP machine must heat the water more aggressively to prevent the air from cooling down before it reaches the user, which increases water usage. Conversely, a very dry environment, particularly during winter months when indoor heating is running, accelerates the evaporation rate from the humidifier.
The use of heated tubing helps stabilize the air temperature from the machine to the mask, minimizing condensation, or “rainout,” inside the tube. While this feature prevents water from pooling in the hose, the overall system might still draw more water to maintain the desired humidity level. A less obvious factor is the mask seal, as a leaky mask allows humidified air to escape into the room, forcing the machine to compensate by increasing its output and consuming more water.
Water Quality and Care
The type of water used in a CPAP humidifier is important for the longevity of the machine and the user’s health. Distilled water is recommended because the distillation process removes minerals, chemicals, and pathogens. This purity is necessary to prevent mineral deposits, known as scaling, from forming on the heating plate and inside the water chamber.
Tap water contains minerals like calcium and magnesium that, when heated and evaporated, leave a chalky residue. Over time, this scaling will reduce the efficiency of the heating element and can damage the internal components of the machine. Additionally, using tap water aerosolizes any trace chemicals or bacteria it contains, which are then inhaled directly into the lungs.
For hygiene and maintenance, the water chamber should be emptied and refilled with fresh distilled water daily. This simple action prevents the stagnant water from becoming a breeding ground for mold and bacteria overnight. Running the humidifier until it is completely dry should be avoided, as it can cause mineral scorching or potentially damage the machine if the heating element remains on without water. Weekly, the water chamber should be thoroughly cleaned with warm, soapy water or a vinegar solution to remove any mineral residue.