It doesn't tell you. If you turn the head upside down, you will be able to see that the stainless steel spout will pry out. Take it out and you will find the charcoal filter.
By Conrad Noel
the carbon is in a small bag type and slips up into the space where the water drip down into the reservoir (blue container). It just fits up into it. To change just pull the one that is in there out and replace.
And yes the instruction manual is not very clear on several things and of course as I discussed before there is no number to contact the manufacturer or retailer and no website for them. I did some looking around at different models and since I use it for making distilled cpap water I do not use the charcoal carbon filter.
By Baron Rockefeller
I had trouble figuring that out also. The spout comes down and you will see the carbon filter is all ready installed. When you need to replace it, it will be easy to do by gently pushing down on the silver part of the spout.
By Leona Housman