A sleep medicine doctor prescribed me an ASV (adaptive servo ventilation) machine that must use DISTILLED water. Airports sell bottled water with natural minerals, NOT distilled water. Do I need a prescription to bring distilled water?

I fly for work, usually to European Union, British Isles, Asia, Middle East (mostly Abu Dhabi, Bahrain, Doha, Dubai, Israel) , North America.

Medically necessary Distilled Water dumped by TSA - FlyerTalk Forums

My distilled water was thrown away.

Query: CPAP, Distilled Water, Oxygenator, in carry on. - FlyerTalk Forums

Don't bother trying to get distilled water through security.

It always takes me a couple of days to find a decent grocery store when traveling so you need a plan to hold you over for a few days while you acquire distilled water.

According to my MD, the biggest risk in using non-distilled water is the bacteria that causes Legionnaires' disease. Who knows? Some water supplies contain this bacteria (and others). Breathing bacteria water is not so groovy.

Based on my experience, tap water that is high in mineral content will add scale to your CPAP's water chamber. Tap water from areas using ground water contaminated by industrial activity (like anywhere in Texas where they are pumping crude oil) fouls the air you breath. Tastes bad (rotten eggs)! Yuck. Chicago tap water is often this bad. It isn't just Texas.

This leaves bottled water. According to Consumer Reports, bottled water is often no better than tap water. Depends on brand and bottling plant.

Desani bottled water is my first choice. Available at fine McDonalds everywhere.

Second choice Aquafina then Ozarka. My choice isn't particularly scientific. These seem to be the most consistent in terms of taste, clarity, and availability.

If you want to get scared about bottled water quality go to http://www.nrdc.org/water/drinking/bw/bwinx.asp

Some hints about making your trip through airport security a bit more efficient. You have to run your CPAP through the xray machine. The TSA will want to check it for bomb residue. If you have it enclosed inside of a suitcase or roller bag, TSA will have to swab the CPAP and the bag and the stuff inside the bag. Basically, your bag gets searched.

I've started treating my CPAP like a laptop. I take it out of the bag. I don't take out the hose, face mask, or power cord. Now, I'm not keen on having my breathing machine exposed to the germ infested environment of xray buckets, inspection tables, etc. To solve that little problem, I have a drawstring closing bag (small version of a sleeping bag stuff bag). Then my CPAP is protected from prying eyes and germs. Gets me through security faster. they just swab the CPAP a couple of times, stick the cloth thing in the machine and I'm on my way. Everyone is happy.

One other thing. TSA seems to be getting used to CPAP machines. While they don't know necessarily what they are used for, they are not surprised to see them. As soon as I've been assigned a secondary screener, I tell them it is a CPAP machine. They probably already know that but I get some small comfort in stating the obvious anyway.

  • 1
    I know it’s a hassle, have you tried putting distilled water in travel sized Iiquid carry-on containers? I s does not leave room for much else in your quart sized ziplock bag allotment. But, it may work as a stopgap.
    – Dean F.
    Oct 3, 2020 at 23:52
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    Do you need to use the device during flight? I would be surprised if it is not very easy to buy a bottle of distilled water at your destination. Oct 4, 2020 at 1:35
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    @Tor-EinarJarnbjo: Or you can put a larger bottle of distilled water in your checked luggage. And even if you do need to use it on the flight, how much water does it need for that length of time? Maybe that much will fit in your 1L bag. Oct 4, 2020 at 2:13
  • Another possibility would be to bring equipment to purify the water airside at the airport. High temperatures are supposed to kill Legionella, so you could start with a cup of boiling water from a coffee shop, and then use some sort of commercial purifying filter for the minerals. It won't be as pure as distilled but it might be a lot better than ordinary bottled water. Oct 4, 2020 at 2:15
  • 3
    Have you asked your sleep doctor? Surely they've had patients that have had to deal with this problem in the past?
    – Midavalo
    Oct 5, 2020 at 2:25

1 Answer 1


In the USA there's TSA https://www.tsa.gov/travel/security-screening/whatcanibring/items/medications-liquid

In Canada it's CATSA https://www.catsa-acsta.gc.ca/en/medication-and-medical-items

In Germany, we can look Frankfurt Airport https://www.frankfurt-airport.com/en/faqs/overview-faqs/faq-hand-luggage.html

None of these require a doctor's note. All of them require you to present your stuff to the screening officers. An official label is super helpful, to quote CATSA

You are not required to bring documentation to support your medical needs or condition. However, if you feel that it would help ease your screening, it should be presented to the screening officer along with your medically necessary items.

Prescription medications and essential non-prescription medications are exempted from the 100 ml or 100 g (3.4 oz) limit and do not have to be placed in a plastic bag. However, we recommend that these items be properly labeled (manufacturer's name or pharmaceutical label identifying the medication).

So don't just put your liquid on the belt and begin to explain after rather talk to the officers before. Much as pilots have the "Aviate, Navigate, and Communicate" credo, communication should be high on your priority too. To quote CATSA again

If you need assistance, please inform the screening officer when you arrive at the checkpoint.

Despite the stupid regulations binding their hands , staff at checkpoint are also humans. Treat them with respect and it'll be fine. Allow extra time and be very patient. One little tip: I'd call it "special treated water for medical purposes" or similar. This is not a lie, it's more of an assistance for people who never needed to learn the difference between purified and distilled water.

Since you mentioned the Middle East, let's check Dubai https://www.dubaiairports.ae/before-you-fly/baggage/baggage-regulations

Exemptions will be made for medication, baby milk/foods and special dietary requirements to be used during your trip.

Same everywhere.

Of course, the UK has stricter rules, because it's the UK. https://www.heathrow.com/at-the-airport/security-and-baggage/hand-baggage-and-liquids

Liquid medicines: You are only permitted to carry quantities of liquid medication in excess of your personal liquid allowance where it is needed during the course of your flight. All medication should be accompanied by documentary proof of authenticity, such as a prescription or letter from a medical practitioner confirming that you need them for your journey. Liquid medication that is not required on the flight should be carried as hold luggage

  • "Aviate, Navigate, and Communicate" means that communication is LOW on the priority list, not high on it! It is literally last on the todo list.
    – Doc
    Aug 20, 2021 at 4:28
  • This actually demonstrates (again) how silly the liquid rules at airports really are... Aug 20, 2021 at 6:40
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    It sure is. When it was introduced there was an article, I remember sharply, when a security researcher went through with two huge unmarked bottles and when asked what it is he answered "oh, contact solution" and that was it.
    – user4188
    Aug 20, 2021 at 7:12
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    @Doc it's on the List and the list is only three items long. The really unimportant things didn't make the List.
    – user4188
    Aug 20, 2021 at 7:12

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