Mineral buildup and scaling can occur over time due to the heating element coming into contact with hard water. To prevent this, it is recommended to regularly descale the Philips Avent SCF355 bottle warmer. Prepare a descaling solution by mixing equal parts water and white vinegar. Pour the solution into the empty bottle warmer, ensuring it covers the heating plate. Switch on the warmer and let it run for approximately 10 minutes. Afterwards, thoroughly rinse the unit with clean water and wipe it dry. Performing this descaling process every 4-6 weeks will help maintain the longevity and performance of the bottle warmer.