A strange problem with BWT Initium 2.5 l filter's scale Is there anyone, who has BWT Initium 2.5 l filter and can explain me, what is going on with their scale?

​When I fill it with water and wait until it filters out to exactly 1000 ml​ mark​ and then pour this water to another vessel with scale, it turns out, that I actually have 700-800 ml. ​By analogy, ​when I filter exactly 1500 ml on BWT Initium scale and pour that water out, I can get 1,2 liter at most.

Is there anyone, who could explain me this magic?

​I've been using many filters before BWT Initium and when filter scale showed 1500 ml, I could pour 1,5 liter kettle to the top. This is my first product, that has so strange scale.​
Reply just received from pot's producer. In case someone would be interested about &quot;the magic&quot;:

The scale with 2,5l just applies to the empty jug without funnel and cartridge. So the funnel with cartridge inside displaces the water in the jug. I just tried this out with my own Initium jug.
If you fill in 1000ml it´s the same amount of water, but it will be e little bit more at the scale.
I know, this is a little bit confusing, because the measurement can be read as the amount of filtered water. I´m very sorry for that. But I guess this explains the “magic” in this case.