Well, it depends on a few things - what water you use, how good you are at flushing your machine after every use... But in general, we recommend descaling about every 300-400 pods.
How To Descale Your Machine
Mix 125ml of Caffetto Organic Descaler with 875ml of water to make a 1 litre descaling fluid. Follow the machine manufacturer's instructions to decalcify the machine. Always rinse the machine thoroughly with fresh water after decalcifying and before refilling and reusing the machine.