Lining your kitchen caddy with a compostable bag is optional. A sheet of paper towel in the bottom of the caddy, or a quick rinse after emptying will work just as well.
Food scraps can go in your kerbside FOGO bin (lime-green lid) loose, not in a bag. The food scraps and garden waste are not separated before the composting process, so it doesn't matter if they get mixed up in the bin.
Only use 100% corn starch compostable bags in your kitchen caddy because they won't contaminate your FOGO, and will fully decompose.
To avoid contaminating the FOGO stream, use the bags supplied by Council and available, free of charge, from transfer stations and other Council facilities (see list below).
Remember: even though these bags are compostable, there are resources involved to produce and transport them, so minimise their use when you can.