APM6855 Usual problem, but how to drain the defrost tank?

Hi everyone,
I have an APM6855 and have the usual problem where the fridge is showing H and after a defrost works ok for a couple of months or so.
I have noticed the water from defrosting disappears into a small hole into what I assume is a tank at the bottom of the freezer. This cant be a bottomless tank so does anyone know wher this can be drained ?

Thanks
steve at nextdaytelecom.co.uk