Why does toilet cleaner fade when put into mineral water bottle?

This is directly related to the frequency of going to the toilet. The higher the frequency, the faster the color fades.

Slag settling is normal after all. Generally, the tablets are placed in the farthest corner from the water outlet and surrounded by two fist-sized pebbles, which has two advantages: to prevent the melted tablets from going away with the water and causing excessive consumption. Two stones can save water.