Pouring boiling water into a cold bowl can cause the porcelain to crack instantly, leading to expensive repairs or a flooded bathroom. Additionally, the intense heat can melt or damage the wax ring that seals the toilet to the floor, causing leaks. The Safe Alternative: Hot (Not Boiling) Water
Sudden exposure to extreme heat can cause "thermal shock," leading the porcelain bowl to crack or even shatter violently. unblock toilet boiling water