Assalaamu alaykum. I poured a bit of Zamzam water along with some purified water that was boiled and contained medicine. I could not finish the last gulp, so I poured all of it down the drain. Is it haram to pour a bit of Zamzam water mixed with other ingredients down the drain?

All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

Zamzam water is respected and worthy of reverence. Therefore, many scholars stated that it is disliked to use Zamzam water to remove impurity with it. This is similar to pouring it in an impure place such as the drain and the like. Hence, what you did is disliked, and you should not do it again. Rather, Zamzam water or the water over which Quran was recited should be poured in a place where it is not exposed to disrespect.

Allah knows best.