Modern toilets are made of porcelain, which is a type of ceramic. While durable, porcelain expands when heated. If you pour boiling water (212°F / 100°C) into a cold toilet, the sudden thermal shock can cause the porcelain to crack. At best, you get a hairline crack. At worst, the bowl shatters violently.
Heat your water to the correct temperature (hot tap water or cooled boiled water). Stand to the side of the toilet (not directly over the bowl) and pour the water slowly from waist height. The force of the pour helps push the water through the trap, while the heat does the chemical work. unblocking toilet with hot water
Do not flush immediately. Let the hot water and soap sit for 10–15 minutes. The heat needs time to soften the blockage. You may see the water level slowly start to sink—this is a great sign that the clog is dissolving. Modern toilets are made of porcelain, which is
Tip: Pour from a height of about 2–3 feet (60–90 cm) above the bowl to create pressure, but avoid splashing. At best, you get a hairline crack