Handcoffee machines heat water like a kettle, so all you have to do is maintain your machine like your kettle.
Pour white vinegar instead of water into the machine's reservoir and start the cycle to descale it, then rinse it several times with clean water to remove the vinegar taste.
It is advisable to descale the machine regularly (every 2 months or 100 coffees) to increase its performance and lifespan.