Why is distilled water recommended to prevent scale build-up in steam kettles?

Distilled water is recommended for use in steam kettles primarily because it contains no minerals that contribute to scaling. When water is heated and steam is produced, any dissolved minerals, such as calcium and magnesium, can precipitate out and form scale on the internal surfaces of the kettle. This scale build-up can impair the kettle's efficiency, lead to increased maintenance costs, and even cause potential failures if not addressed.

Using distilled water eliminates these mineral contaminants, thereby significantly reducing the risk of scale formation. This practice helps maintain the integrity and performance of the steam kettle, ensuring that it operates effectively over a longer period. While other options may touch on aspects related to water usage, they do not specifically address the core issue of scale prevention in steam kettles as effectively as the correct choice.