Beko Dcu 7230 - water tank says full when not?

Hi, my dcu 7230b is playing up. It runs for about a minute then stops and displays a warning light that the water tank is full but its not. I tr ied to remove the back and in the process of doing so I tilted it forward which caused water to leak out from underneath. This caused me to think there is another tank somewhere which may actually be the problem however iI havent been able to get into it to find out. Anyone k n ow if this is the case and if so, how to get at it?

Incidently, since the water ran out its run longer so I think im onto something.
Cheers Paul