5 TrustPilot Rating


The importance of using distilled water with your CPAP Humidifier!

Have you recently purchased a humidifier for your CPAP machine? Then you might be wondering why it is advisable to use distilled water to fill up the water chamber of your humidification system. Find out below whether standard tap water could be a substitute.

Unfortunately, standard tap water is not ideal for your humidifier. Tap water can leave hard white mineral deposits in the chamber. This is due to evaporation, which can potentially lead to mold growth.

It is therefore very important that you try to use distilled or purified water every time you fill up your humidifier water chamber. If distilled water is not easily accessible to you, then you can opt for bottled water instead.

Wondering how to get the most from your humidifier? Read our maintenance advice below! Wondering how to get the most from your humidifier? Read our maintenance advice below!

Can I use boiled tap water or filtered water instead when filling up my CPAP humidifier chamber?

Boiling water generally kills microbes, but it will not remove minerals or chemical contaminants. Filtered water may remove some of the minerals, but may not remove living organisms or other chemicals. It is therefore advisable that you opt for distilled water. This will maximise the life of the water tub and reduce mineral deposits.

Why it is important to maintain regular cleaning of my CPAP water chamber?

It is important that you keep your water chamber as clean as possible to avoid any deposits building up. You should clean your water chamber on a daily basis. When cleaning, make sure that the water in the chamber is emptied fully every morning.

If you wake up to find that you haven’t used all of the water in the chamber the night before, it is important that you don’t reuse this water. You should empty unused water out of the tank, for new water to be added the following night.

How can I most effectively clean my CPAP humidifier water chamber?

To ensure that your water chamber lasts for as long as possible and remains hygienic to use, it is vital that you clean the water chamber daily. You can do this by washing it with warm water and a mild detergent.

Once a month, you should take a thorough look at your water chamber. You should check for deterioration, cloudiness, a build-up of hard white mineral deposits or mold. If you find that you can’t clean these deposits, then it is advisable that you consider purchasing a new water tank. Water tanks can normally be purchased separately. To find a replacement chamber for your humidifier, click here.

To ensure that your water chamber is thoroughly clean, you might want to check if your water chamber model is dishwasher safe for a deep cleanse once a week. You can disinfect your humidifier by soaking it in a solution of vinegar and water. 1/5 of the solution being vinegar and the rest water. Leave it to soak in the solution for up to 30 minutes, then thoroughly rinse it with water and leave it to dry. Make sure when you leave it to dry, it is out of the way of direct sunlight.

Things to avoid cleaning your CPAP humidification system water chamber with:

It is important that you don’t clean your humidification system water chamber with any substances that would be harmful to breathe. This includes bleach, chlorine, alcohol and other potentially harmful substances to breathe.

Author: Helen Clarkson

About author: Helen Clarkson is a Sleep Specialist at Baywater Healthcare. Ms. Clarkson has worked with Baywater since 2008, working closely with patients in delivering sleep/bi-level services including sleep and respiratory, both in the home and clinic setting. This includes therapy initiation and troubleshooting support. Ms. Clarkson is responsible for delivering the Baywater Healthcare patient adherence management programme to ensure continuing patient therapy compliance. works in conjunction with NHS clinicians and procurement to deliver excellence in home and clinic-based services. She provides training on all aspects of sleep including devices and interfaces. Previously, Ms. Clarkson served as Respiratory Physiologist at Pontefract General Infirmary. Her position was Senior MTO for lung function/sleep department, and she was responsible for performing simple and complex sleep studies, sleep study analysis, CPAP initiation, therapy adherence and troubleshooting/service clinics, spirometry, lung volumes and transfer factor, reversibility, CPET, hyperventilation testing, EIA testing, skin prick testing, 6 min walk tests. She has also held roles as Respiratory Physiologist and Respiratory Technician, working closely with patients with respiratory disorders -- including ex-miners. Ms. Clarkson has a BSc (Honors) in Applied biology from University of Staffordshire. She also studied Developments in Sleep Medicine (advanced course) at St. Thomas’ Hospital, and took the Edinburgh Sleep Medicine course. She completed the BSS: Advanced sleep course and the ARTP NIV Course.

17 thoughts on “The importance of using distilled water with your CPAP Humidifier!”

  • Lori Watts

    Do you have to put water in cpap and if not are there any problems ? I am a nurse and a mbr says he always coughed with using distilled water and stopped using any water and has improved. My concern is also the machine

    • CPAP.co.uk

      Hello Lori, you do not have to use a humidifier with CPAP, it is an optional element that some people find improves their CPAP, mainly because it reduces or prevents a dry mouth. In fact only around one in three people do need a humidifier, so if your patient is happy without using one then that is no problem. The important thing is they're happy and comfortable with using CPAP.

  • Alvin

    cpac lately its hard got bad cough this coming week ill be in hosp for test . I learn something here I do every other day clean mask and house but what I learn is change water everyday I use purrafied water

    • CPAP.co.uk Admin

      Hello Alvin, thank you for your comment. We do recommend changing the water each night as heated water is an ideal breeding ground for bacterial. However that does not mean it is necessarily related to your cough, though it could have been a factor. We hope you get better soon!

  • Mick

    How bad is Chlorine content in tap water ? Would it give you long term lung disease from inhaling low content in evaporated chlorine?! Just wondering?!

  • Lawrence Neill

    I just got a CPAP machine yesterday. When I was being instructed on the machine, they kept referring to demineralized water for the humidifier. I most commonly find in stores is distilled water. Is there any difference between the two? Should I use one over the other?

    • Tim

      Hello Lawrence, the reason that is recommended is to avoid limescale and mineral deposits in the humidifier chamber and the CPAP machine. Ultimately as long as the water is low in mineral deposits, whether it is demineralised, distilled or even simply filtered, it should be absolutely fine and help ensure that your humidifier and CPAP are not at risk from the build up of these minerals.


    My son had a science project when a child that was designed to use different types of water to grow plants. I had to test the ph of all. I am very concerned that the ph of the distilled water was 4.0. This is a strong acid. What are the ramifications of breathing an acid nightly?

    I filter my water for my CPAP machine, but am aware of the possibility of the presence of bacteria. My filter unit is charcoal based.


    • Tim

      Hello, thank you for that comment which is very interesting. CPAP manufacturers and, more importantly, medical professionals have always recommended the use of distilled water and we would therefore like to think it is safe. While the pH of 4.0 you mentioned would be alarming, typically the pH of distilled water would be between 6 and 7; it should be neutral when first produced but once it comes into contact with carbon dioxide it does absorb some and become very slightly acid - about the same level as tap water. We are not sure what caused the water in your test to have sch a high reading but having looked into this, that result does not seem typical so hopefully was just an anomaly. It is certainly something worth having more research into though.

  • Ron Friedman

    I will be visiting Southampton in November. Where can I buy distilled water?

    • Kelly

      Hi Ron,

      Apologies for the delay in responding to you. You can purchase distilled water from a local chemist, not a chain such as Boots or SuperDrug. Alternatively you can purchase filtered water from the supermarkets.

      Customer Care Team
      Intus Healthcare

  • Bill Robertson

    When I use my machine my sinuses swell up under my eyes, any idea as to why.

    • Giny Humbles

      Hello Bill, you might want to clear your sinuses before using your CPAP machine. You can do so with the SinuPulse Elite Nasal Irrigator byHealth Solutions: https://www.sinupulse.co.uk/sinupulse-elite-nasal-sinus-irrigator.html
      Which machine do you use? Is that a fixed pressure machine or an automatic?

  • Joe

    Is it okay to put my mask and tubing on the dishwasher to clean it?

    • Giny Humbles

      Hello Joe, We would not recommend to put your tube and mask in the dishwasher. It is recommended to clean your mask daily in mild soapy water. You can do the same with your tube, once a week.
      You might want to consider SoClean 2 CPAP Sanitiser. SoClean kills 99.9% of CPAP germs and bacteria in your mask, hose and reservoir with no disassembly, no water, and no chemicals. It's the safer, healthier way to breathe cleaner.

      The most common cause for red marks and skin irritation on the face is bacteria on the CPAP mask cushion. Even a visibly clean mask can have bacteria growing within the surface.

      SoClean is the simple way to sanitise all of your equipment and kill 99.9% of bacteria, ensuring it is hygienic and odour-free.

Leave a Reply