A continuous positive airway pressure (CPAP) machine is a common treatment for sleep apnea, delivering pressurized air through a mask to keep the user’s airway open during sleep. Many CPAP devices include a heated humidifier, which adds moisture to the air stream to prevent common side effects like a dry throat, nose, or mouth. This humidification process significantly improves comfort and compliance with therapy. The choice of water is of considerable importance, as it affects both the long-term functioning of the machine and the health of the user.
The Essential Water Type for CPAP Humidifiers
CPAP manufacturers and experts unanimously recommend distilled water. Distillation is a process where water is boiled into steam and then condensed back into liquid form. This effectively removes nearly all inorganic compounds, minerals, and microorganisms.
The absence of minerals, such as calcium, magnesium, and iron, is the primary reason for this recommendation. When mineral-containing water is heated, the water evaporates, but the mineral solids are left behind. These residual solids accumulate over time, forming a hard buildup known as scale or calcification on the heating plate and reservoir walls.
Using distilled water prevents this mineral buildup, which is crucial for maintaining the machine’s efficiency. The heating element remains clean, ensuring consistent humidification, and the humidifier chamber stays clear of deposits. This practice protects the internal components of the device, helping to prolong its lifespan and ensuring the warranty remains valid.
Risks of Using Tap Water or Bottled Water
The most significant risk of using non-distilled water is mechanical damage to the CPAP unit. Tap water and many bottled waters contain varying levels of dissolved minerals. Regular use causes these minerals to coat humidifier components, forming thick deposits that reduce performance. This scale interferes with the heating element and can lead to machine failure.
There are also considerable health risks associated with introducing non-distilled water into the CPAP circuit. Tap water is not sterile and often contains trace amounts of microorganisms, including bacteria like Pseudomonas and fungi. When this water is heated and converted into a fine mist (aerosolized) by the humidifier, these pathogens can be directly inhaled into the user’s respiratory tract.
The respiratory tract lacks the strong defense mechanisms, like stomach acid, used by the digestive system to kill ingested microbes. Inhaling contaminated mist can lead to respiratory irritation and, in rare cases, serious infections. Furthermore, minerals and chemicals like chlorine found in tap water encourage the growth of biofilms and mold within the chamber and tubing.
Handling Water Shortages and Temporary Alternatives
In situations where distilled water is temporarily unavailable, such as during travel, certain alternatives can be used cautiously. The best short-term substitute is purified bottled water, which has undergone filtration to remove impurities. However, purified water may still contain trace minerals, so it is not a long-term replacement for distilled water.
If neither purified nor distilled water is available, tap water may be used as a last resort, but it must be prepared first. Boiling tap water for one to five minutes and allowing it to cool completely will kill most harmful microorganisms. This boiling process does not remove minerals, meaning the risk of machine damage from scale buildup remains.
Any alternative should be used only for a brief period as an exception. If a substitute is used, the humidifier chamber must be thoroughly cleaned with soap and water immediately afterward. Users should return to using distilled water once it becomes accessible to protect both their machine and their respiratory health.