The filter in the Xiaomi Faucet Water Purifier turns green or yellow over time due to the interception of impurities and contaminants present in tap water. The ceramic filter effectively captures these particles, and the discoloration is a sign that the filter is performing its intended function.
If you notice impurities or color changes, it indicates that the filter is actively working to remove contaminants. You can clean the filter if foreign matter accumulates. Regular cleaning is particularly important if you see algae or similar substances, as they can be challenging to remove if left for an extended period. After cleaning, the filter will continue to function normally, ensuring that you can use the purifier with confidence.