The bathroom in the HDT cottage has a regular (looking) toilet.  Looks however can be deceiving, this is not merely a flush - and down it will go device.  The toilet itself sits on a pedestal and is flushed  using a foot pedal, which regulates the amount of water used in the flush.  The contents head for a macerator unit and then journey to the Phoenix - the large blue bin located in the greenhouse.  It's been said that this bin only needs to be emptied once a year for a family of four. 

It looks like a regular biffy

The Saniflo macerator unit - a Cuisinart for compost

Big Blue is where the goods are stored. Mark and Jim deliberate next steps.