Stalactites fill cauldrons with mineral water, which is used for brewing

At Minecraft Live, it was announced that placing a cauldron underneath a stalactite would collect the water drops and create "renewable water". But, we clearly already have easier and faster methods of getting infinite water.

I suggest that a cauldron that fills with water from a stalactite would allow you to fill a bottle with mineral water — after all, stalactites often form due to mineral-rich water leaving behind deposits. Adding regular water using a bucket would replace the mineral water. Mineral water would act like a base potion, like an awkward potion, used to brew a whole new batch of stronger or unique potions.

This would restore the cauldron's usefulness (since all of its redstone uses have been replaced by the cheaper and slightly more versatile composter), and make the cauldron actually indispensable for some brewing recipes.