A Continuous Positive Airway Pressure (CPAP) machine treats obstructive sleep apnea by delivering pressurized air to keep the airway open. Many devices include an integrated humidifier, a reservoir that adds moisture to the airflow. This humidification prevents common side effects of dry air, such as nasal congestion, irritation, and a dry throat. The type of water used in this chamber significantly affects both the machine’s performance and the user’s health.
Damage to CPAP Equipment from Mineral Buildup
The primary consequence of using non-distilled water is the rapid accumulation of mineral deposits, known as “scaling.” Tap water and most bottled waters contain Total Dissolved Solids (TDS), primarily minerals like calcium, magnesium, and iron. Distilled water has an extremely low TDS count (around 2.5 ppm), while typical tap water ranges from 50 to 500 ppm.
When the humidifier heats the water, pure water evaporates, but the mineral solids remain behind. These solids precipitate and solidify onto the heating plate and chamber walls, creating a hard, chalky crust similar to limescale.
This mineral crust acts as an insulator, reducing heat transfer from the heating element to the water. The humidifier must work harder to achieve the desired moisture level, leading to reduced efficiency. Over time, scaling can permanently damage the heating element or the chamber, shortening the equipment’s operational lifespan. Buildup can also impede small parts, such as seals and O-rings, causing potential leaks or poor performance.
Health Risks from Inhaling Contaminants
Using non-distilled water introduces health concerns related to inhaling mineral particles and exposure to biological contaminants. When mineral-rich water is heated, microscopic mineral particles (dried remnants of TDS) can become aerosolized. These particles are then carried through the CPAP tubing into the user’s airways.
Inhaling these fine, aerosolized particles can irritate the sensitive lining of the nasal passages, throat, and lungs. This irritation can worsen symptoms like congestion and dryness, which the humidifier is meant to alleviate.
Biological Contaminants
A more concerning risk involves biological contaminants present in tap or bottled water, which the Centers for Disease Control (CDC) classifies as “unsterile.” Tap water can harbor various microorganisms, including bacteria (Pseudomonas aeruginosa, Legionella species), fungi, and protozoa (Acanthamoeba). The warm, moist environment of the CPAP humidifier is an ideal breeding ground for these pathogens, allowing them to multiply and form biofilms. As air passes through the chamber, these microbes can be aerosolized and inhaled directly into the lungs, potentially leading to serious respiratory infections.
Short-Term Water Alternatives and Cleaning Protocols
If distilled water is unavailable, the only acceptable short-term alternative is using tap water that has been boiled and completely cooled. Boiling the water for at least a minute effectively kills most biological contaminants, reducing the risk of inhaling live bacteria or viruses. However, boiling does not remove minerals; it concentrates them, meaning scaling will occur more quickly than with unboiled tap water.
Because this alternative causes mineral buildup, it should only be used as an emergency measure for one or two nights. To address resulting mineral deposits, regular cleaning of the water chamber is necessary.
A highly effective method for removing limescale is soaking the chamber in a solution of white household vinegar and water. Use a solution of one part white vinegar to three parts water, allowing the chamber to soak for about 30 minutes. The acetic acid dissolves the calcium and magnesium deposits bonded to the surfaces. After soaking, the chamber must be thoroughly rinsed multiple times with fresh water to ensure no vinegar residue or odor remains before reuse.