If you have plastic pipes, avoid the boiling water method. Instead, try these safer, effective alternatives:
A cheap, plastic barbed wand can manually pull out hair and debris from the first few inches of the drain. boiling water down drain
Most modern homes use PVC (polyvinyl chloride) for drain lines. PVC is rated to handle temperatures up to 140°F (60°C). Boiling water is 212°F (100°C). Pouring boiling water directly into a PVC drain can soften the plastic, warp the pipe, or melt the seals and glue at the joints. This leads to slow leaks behind walls or under sinks that may go unnoticed until mold develops. 2. Porcelain Sinks and Toilets If you have plastic pipes, avoid the boiling water method
Boiling water is generally safe if you have older, heavy-duty plumbing systems, specifically: PVC is rated to handle temperatures up to 140°F (60°C)
Boiling water works primarily through heat transfer. Most kitchen clogs are caused by FOG (Fats, Oils, and Grease). When these substances are warm, they are liquid; as they cool, they solidify into a waxy sludge that traps food particles.
Even if you have metal pipes, the rubber seals and gaskets inside the P-trap (the U-shaped pipe under the sink) can be degraded by repeated exposure to boiling water, leading to persistent leaks. When Is It Safe to Use?