Many people believe that pouring hot water into the sink helps remove grease and unclog drains. However, this habit can actually cause several problems.

The Effects of Pouring Hot Water Into the Sink

1. It Accelerates Pipe Aging

Most kitchen drainpipes are made of plastic. Although some types of plastic can withstand heat, repeatedly pouring boiling water down the drain can cause the pipes to age much faster than normal.
As the pipes deteriorate, you’ll likely face more frequent repairs or even have to replace them entirely, increasing maintenance costs.

2. It Can Warp or Crack the Pipes

Not all drainpipes are made of the same quality materials. If your home uses PVC pipes, be cautious — these pipes generally cannot tolerate temperatures above 60°C (140°F).
Meanwhile, boiling water or vegetable blanching water can reach 90–100°C (194–212°F). When such hot water is poured into the sink, it can cause the pipes to deform, warp, or even crack over time. This may lead to water leakage, kitchen cabinet damage, and unpleasant odors.

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How to Remove Grease from Drainpipes Safely

Instead of using hot water to clear grease buildup or unclog drains, consider these safer methods:

• Never pour oil or grease into the sink. When hot, grease is liquid, but as it cools, it solidifies and sticks to the inner walls of the drain, causing blockages and bad smells.

• Use enzymatic drain cleaners. These products contain dissolving enzymes that can emulsify and break down grease, preventing it from forming thick layers inside the pipes.

• Apply regularly. Enzymatic cleaners can flow through the entire pipe length and remove buildup effectively while also killing bacteria.

Before using any cleaning product, read the instructions carefully and choose those from reliable brands with clear ingredient lists to ensure safety for both your plumbing system and your health.