We had two bins: one recycling bin and one for residual waste.
After a while I figured out that the residual waste bin was only half full when it was emptied and the recycling bin had heaps of space left even if it was emptied every fortnight.
After a call at the City Council I understood that I just need to buy plastic rubbish bags, I can put them at the street every week. For our family one bag every fortnight is fine.
The recycling bin: What to do with the left over space?
We asked our neighbours and they are happy to share it with us.
One bin, two happy households! :-)