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Water in the Mask + Hose known as 'rainout'

Rainout from CPAP Humidifier


Are you Getting Water in the Mask or Hose - commonly known as 'Rainout'?

This is the biggest complaint when using humidifiers, but usually an easy one to fix.

When water collects in the hose and often enters the mask, this is known commonly as 'rainout' and is caused by the heated water from the humidifier reacting with the cold/cooler temperature in the bedroom. Sometimes people aren't even aware they have water in the hose if it's not reached the mask, but will usually experience loud strange noises from the machine. There are several causes and solutions for this:-

The Humidifier and Machine Needs Positioning Lower Than Head Height and the Hose Elevating

If droplets start to form in the hose and it is raised with the machine and humidifier lower than head height, gravity should cause any water to drip back down into the water chamber rather than into the mask. (As well as helping with 'rainout' having the set-up like this will prevent the hose dragging the machine off a bedside cabinet that's too high).  Do not place the machine on the floor though as more dust circulates down there, even in the cleanest of bedrooms, and there is also a small fire risk which is why the manufacturers warn against placing on the floor or any flammable surface.  It can also be a trip hazard and could get damaged.

If your bedside cabinet is too high, consider if it's possible to have the legs chopped off to lower before going to the expense of buying a new cabinet. Some people purchase the CPAP Bedside Holder which slips under the mattress for this reason, and in fact many people use this for when travelling as these days only a very small bedside table is provided in hotels - if at all.

CPAP Bedside Holder


To get the hose elevated, you can drape it around the bed's headboard, but a more popular solution is the Hose Lift as it has a coil that turns as we move around in bed so prevents the drag of the hose that can even happen draped around the headboard, and especially if it's a material covered one. Incidentally the Hose Lift and Bedside Holder is made by the same manufacturer, Arden Innovations.  Just like the Bedside Holder, the Hose Lift is also designed to collapse easy and is very light for travel.


The Hose Needs Insulating

This is the main cause of the 'rainout' as the heated humidified water enters the cold hose tubing. The Hose Covers provide insulation and the fleece ones are the best for this, which is why our manufacturer uses micro fleece only for the best insulation. Not only do they help with 'rainout' but many of us prefer our hoses covered to take away the clinical look from the bedroom.

Hose Covers in Various Lengths, Colours & Patterns

Hose Covers

If you are using a mask that has an additional small hose tube which attaches to the larger one, then you will also need this smaller hose insulating as well or will defeat the object of all round insulation.

Mini Hose Covers in Various Lengths, Colours & Patterns

Mini Hose Covers


Heated Hoses are another solution and particularly good for very cold bedrooms or countries, but in most cases they aren't needed here in the UK unless 'rainout' is a particularly bad problem.  Some people also find the heated hoses too hot for breathing so only use them in the winter.  Note that not all machine manufacturers support a heated hose, but a lot of the newer ones do! Fisher & Paykel call theirs 'thermosmart,' Resmed the 'climateline' and Philips Respironics simply a 'heated tube.' Drive DeVilbiss don't have heated hoses for their machines but the Hybernite Heated Hose can be used with this and also with the Lowenstein Prisma machines and others that have no specific heated hose.

We do have a range of heated hoses at the charity in the Hose Section on the website.


Humidifier Settings

One of the biggest issues we find is that most machines are set on the default of automatic humidification.  In many cases this automatic humidification setting works well, but in a lot of cases it doesn't!  Please check your manual to see if you can change the humidifier default to manual from automatic, or if you're using a Philips Respironics machine or Resmed, there's further help below:-

Philips Respironics name their automatic setting on the DreamStation series 'adaptive humidification' which can be changed to 'fixed.'  (See the following video for changing the DreamStation Humidifier). Please note that this setting is not available on the newer black DreamStation 2 machine - only the white one.

Resmed call their AirSense 10 series 'automatic climate control' but this can be changed to 'manual' if you are using their climateline heated hose.
(See the following video to change the AirSense Humidifier to manual).

Ensure the Bedroom is not too cold

Try not to let the bedroom temperature get too cold as this raises the risk for 'rainout.' An ideal bedroom temperature is around 65 degrees Farenheit (18.3 degrees Celsius), so if you like sleeping with the window open, perhaps close it slightly, or better still altogether.

Turning Down the Humidifier Helps, but not always the ideal solution

Of course, turning down the amount of humidification will help with this, but often at the expense of getting a dry mouth, so whilst it will act as a temporary solution it's not always a good long-term one (see the webinar for tips with dry mouth at the bottom of this article).

You Could be Dehydrated

Being dehydrated can cause more humidification being needed, and we're all advised to drink plenty of water during the day (8 glasses being the recommended amount = around 2 litres).  A good sign of checking if you're dehydrated is if your urine is dark and smells strong. You can also try pinching your skin on the back of your hand and release. If the skin doesn't spring back straight away and remains raised and slow to go back to normal, this is another sign of dehydration. 

Some people are more vulnerable to dehydration, such as those with diabetes or people taking diuretics.  

The important thing to remember is to drink more water than the body loses, hence in hot countries people often carry water with them due to sweating, and gyms have water fountains in them as exercise will cause sweating too.  

Also, eating spicy food and smoking will cause a dry mouth so more water is needed.

The XyliMelts and other Dry Mouth Products can also be used to help with this, which often allows the humidifier to be turned down which are available on the website.



Also see our webinar for tips about dry mouth:-