This Common Drain Mistake Can Wreck Your Plumbing, Plumbers Say—How to Avoid It

Sinks can become a catch-all dumping ground for waste in the kitchen and bathroom, but they shouldn’t be. Many of the things people tend to put down the drain can harm the sink and the home’s plumbing in general, but one of the worst offenders is oil. But why should you never pour oil down the sink, and what should you do with it instead?

We spoke to plumbing experts on how to make sure this substance doesn’t mess with your plumbing in the long term.

Why You Should Never Pour Oil Down the Sink

Experts say cooking oil, grease, and fat should never be poured down the sink, especially after being heated in a pan during meal prep. Oils and grease are in liquid form while warm, but will become a solid, jello-like substance after cooling; this is what will mess up your plumbing.

“It just lays on the bottom of the pipe and everything just kind of drains along the bottom of the pipe, if the pipes are installed properly,” says Patrick Fee, co-owner of Mr. Drain Plumbing. “That grease slowly cools, and it leaves this sticky trail.”

Fee suggests thinking of the oil and grease being like a strip of gummy fly paper in the pipes: Everything you pour down the sink after that sticks to the grease, building up a big clog over time. The resulting obstruction won’t just affect your sink, but rather it can impact the garbage disposal, dishwasher, and bathroom plumbing, too.

“If you have a dishwasher next to the garbage disposal, the dishwasher line ties directly into it, where we’ll find a lot of fruit particles, grease, and things like that,” says Ryan Osterkamp, owner of Quality Comfort Home Services. “That’ll actually cause the dishwasher to not drain and malfunction.”

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What to Do with Oil

Instead of tossing oil down the kitchen sink, Fee advises disposing of it in other ways, such as the grease jar method recognizable from previous generations. He recommends putting the oil in a glass jar or container until it solidifies, then disposing of it later. If you don’t want to keep a container around, just let the hot oil cool and solidify before putting it into the garbage.

“You can use a paper towel to get any remaining grease from the skillet or pot before washing them,” says Mike Henderson, vice president of operations at Mr. Rooter Plumbing. “Then discard the paper towel in the trash.”

Other Things You Should Never Pour Down the Sink

• Rice: The grains will absorb water and expand, causing a quick clog within hours.
• Coffee grounds: The remnants of your daily cup of joe will act like sand in the sink, sitting at the bottom of the drain as water passes by. The grounds will build up over time to eventually cause a clog.
• Spaghetti: This is a common culprit for people who also have garbage disposals paired with their sinks. Spaghetti, spins around the disposal blade, locks it up and doesn’t drain.
• Fruit peels: Apple and citrus peels can stick to the sides of pipes and your garbage disposal, causing a backup.

How to Fix a Sink You Poured Oil Down

Don’t panic if you accidentally poured oil down the sink; it’s easy to alleviate the situation so the grease doesn’t collect and congeal in your pipes later.

1. Pour hot water down the drain or keep the faucet running on hot for about 10-15 seconds.
2. Pour some dish soap in the drain and continue to flush with hot water. This should help the oil remain in its liquid state to keep it moving through the pipes.
3. If a slow drainage starts to happen or a blockage seems to form, contact a professional plumber to inspect the pipes.

“Always remember that the pipes are under the ground—everything is cooler there,” Fee says. “We definitely want to give it a little extra shot of hot water to help flush that down and prevent us from having an emergency backup and an expensive fix.”