The short answer: use a proper descaling solution, run your machine’s built-in descaling cycle, then run a full rinse cycle with clean water. Every three months or 300 capsules, whichever comes first. The vinegar question is where this gets interesting: Nespresso’s own guide says never use it, and a great many blogs publish the vinegar method anyway, one of them openly admitting it ignores the manufacturer. Both sides are describing something real. Vinegar is acetic acid, descaling solutions are citric acid, and those two behave differently against the rubber seals and plastic waterways inside a pod machine. That difference is also what voids the warranty.
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