Continuous Positive Airway Pressure (CPAP) therapy often relies on a heated humidifier to add moisture to the pressurized air, which prevents dryness in the nose and throat. Introducing water into this humidification chamber creates a dependency on a specific type of water to prevent damage to the device. Distilled water is the required choice for CPAP machines because it has been processed to remove nearly all dissolved minerals and impurities. Using standard tap water or other types of bottled water will lead to a rapid accumulation of mineral scale within the water chamber, which can compromise machine function and longevity over time.
Major Retail Purchasing Options
The most convenient sources for single-gallon quantities of distilled water are often large grocery stores, general merchandise retailers, and local pharmacies. These locations typically maintain a consistent stock, making them ideal for routine weekly purchases. The gallon jugs are usually sold at a low cost, often comparable to other types of drinking water.
Finding the distilled water inside these stores can sometimes require looking in a few different sections. While it might be located alongside other bottled drinking water, retailers also frequently stock it in the baby care aisle, as it is commonly used for mixing infant formula. Another common location is near the household cleaning or laundry supplies, due to its use in steam irons and other appliances.
Pharmacy chains and general retailers provide readily accessible single-gallon options. Checking the inventory online before visiting can save time, as distilled water is a high-demand item that occasionally sells out.
Online and Bulk Ordering
For users seeking long-term cost savings or the convenience of home delivery, purchasing distilled water in bulk is an efficient strategy. Major e-commerce platforms offer multi-packs, such as six or twelve one-gallon jugs, which can significantly reduce the per-unit price. This method eliminates the need for frequent trips to physical stores and ensures a steady supply is always available at home.
Specialized CPAP supply websites offer water in various formats, including convenient travel-sized bottles or pre-portioned packs designed for one or two nights of use. While these smaller packages are often more expensive per ounce, they are ideal for travel.
Warehouse clubs are another excellent physical option for bulk purchasing, providing large quantities at discounted prices. They require adequate storage space at home due to the volume of the purchase.
Quality and Label Verification
Distilled water is produced by boiling water into steam and then condensing the steam back into a liquid state, a process that leaves behind virtually all dissolved minerals and salts. This high purity prevents the damaging white, crusty mineral buildup, known as limescale, on the humidifier’s heating plate.
Confusion often arises with other products like purified or deionized water, which are not suitable long-term substitutes. Purified water, typically made using reverse osmosis, may still contain trace minerals, while deionized water only removes charged ions.
Always confirm the label explicitly states “Distilled Water” and avoid labels such as “spring,” “mineral,” or simply “purified,” as these still contain dissolved solids that can harm the machine. For maximum safety, look for water labeled for use in medical devices or appliances.
Contingency Planning for Shortages
If distilled water is temporarily unavailable, a short-term contingency plan is required to avoid interrupting CPAP therapy. In these rare instances, using bottled purified water is the best immediate alternative, as it contains significantly fewer minerals than tap water. This should only be used for one or two nights maximum to minimize mineral deposition in the chamber.
As a final, short-term measure, tap water can be boiled vigorously for about five minutes and then allowed to cool completely before being added to the humidifier. Boiling neutralizes potential microorganisms, but it does not remove dissolved minerals. Using boiled tap water will result in mineral deposits, so the humidifier chamber must be thoroughly cleaned immediately after returning to distilled water use. These alternatives are strictly for emergency use and must not become a routine practice.