85: A deep dive into distilled water

Why do you put distilled water in your CPAP machine? 

Answer:  The distillation process removes two things from the water–  minerals and contaminants.  Distilling rids water of impurities and more than 99.9% of the minerals dissolved in water.

It’s easy to understand why removing contaminants is necessary.  The water that is used to humidify the pressurized air going into your airway needs to be free of impurities, bacteria, and other microorganisms.  These contaminants may be present in tap water. All water, no matter if it comes from a natural spring, artesian well, or regular household tap, may have trace but safe amounts of minerals, bacteria, pesticides, and other contaminants.

Using distilled water reduces the risk of bacterial growth in your CPAP’s humidifier chamber and the transmission of these contaminants into the air you breathe during CPAP therapy.

Most types of water suitable for drinking, except for the distilled kind, have variable quantities of minerals. Bicarbonate, calcium, iron, magnesium, potassium, sodium, and zinc are some of the most commonly found minerals.

Distilled water is NOT the same as water that has been boiled. When you boil water there is some water vapor that escapes with the boiling. This makes the minerals in the remaining water slightly MORE concentrated than when you started!  So don’t boil water to use in your CPAP machine.  If you CAPTURED the water vapor and then condensed it you would have distilled water.  

Minerals can accumulate on the inside of your humidifier chamber and other equipment.  Mineral build-up is a nice place for bugs (fungus and bacteria) to attach and grow. So mineral-free, contaminant-free distilled water is the best choice for routine use in your CPAP humidifier chamber.

Here is a scientific article published in 2001 showing that mineral levels vary among commercially available North American and European bottled waters.  North American spring waters contained very low mineral levels. North American mineral waters generally contained high levels of Na+ and some contained important levels of Ca2+ and Mg2+. 

Here is what the different types of water mean:  

Drinking water/Tap water is water that is intended for drinking. It is safe for human consumption (swallowing and processing through the stomach and intestines) and comes from a municipal source. There are no added ingredients besides what is considered usual and safe for any tap water, such as fluoride.  To check the quality of your local tap water, check with the EPA.  The Environmental Working Group’s (EWG) Tap Water Database is an excellent resource as well.

Purified water is water that comes from any source, but has been purified to remove certain chemicals and contaminants. Types of purification include distillation, deionization, reverse osmosis, and carbon filtration. Like distilled water, it has its advantages and disadvantages, the advantages being that potentially harmful chemicals may be taken out and the disadvantage being that beneficial minerals may be taken out as well.

Distilled water is a type of purified water. It’s water that has gone through a rigorous filtration process to strip it not only of contaminants but any natural minerals as well. This water is best for use in small appliances—like hot water urns, or steam irons—because it doesn't create the mineral buildup you get with tap water. Though it may seem counterintuitive, this water is not necessarily the best for human consumption, since all of the water’s natural minerals have been removed.

Reverse Osmosis is a water filtration system that has several fine membranes through which water passes. This system may have four or more membranes that remove contaminants and other impurities from your water to the microscopic level. Additionally, it has a mineral filter that ADDS vital minerals into the drinking water, making it healthy for your consumption. Plus, it also tends to improve the taste of water.

Spring water is what you often find in bottled water. It’s from an underground source and may or MAY NOT have been treated and purified. Though spring water sounds more appealing (I imagine spring water coming from a rushing spring at the base of a tall, snow-capped mountain), contaminants have been found in bottled spring water (such as coliform, arsenic, and phthalates). 

Bottom line:  If you are traveling or in a pinch, you might not be able to get distilled water at your destination.  Here are your options:  

• Take distilled water with you (make sure the bottle is travel-safe).
• You can use bottled water (avoid getting a bottle with added minerals).
• Tap water may be an option; tap water is different in different places (see websites above if you want to check your destination water report).  
• You can go without water in the humidifier chamber.

Be sure to replace your humidifier chamber regularly, especially if it appears cloudy or discolored.  Your insurance should cover this, call your company to find out how often.  If your humidifier chamber has mineral scale (this may or may not be visible), this can be removed with a diluted vinegar bath.