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13 Things You Should Never Pour Down the Drain

Everything from olive oil to egg shells can lead to expensive plumbing repairs.

How often do you consider what you're putting down your drain? If your answer is "never," you're not alone. However, when it comes to the health of your plumbing, putting any old thing down the drain can lead to major problems—and expensive repairs—in no time. Before you make a mistake that costs you an arm and a leg, be sure you know these 13 things you should never pour down your drain. And for more on how to get rid of things properly, discover 30 Surprising Things You Should Never Put in the Garbage.


white hands pouring rice into metal sink
Shutterstock/Narin Eungsuwat

Think pouring some leftover rice down the drain is no big deal? Think again. According to Mark Dawson, chief operating officer at Benjamin Franklin Plumbing, absorbent foods, like rice and pasta, "can expand in your pipes and contribute to clogs." If you've got some left on your plate at the end of a meal, make sure you scrape it into the trash can first before rinsing. And for more hidden dangers, check out these 50 Ways You're Ruining Your Home Without Realizing It.

Olive Oil

olive oil pouring into bowl

When you've finished with your olive oil, you should be dumping it in the trash, not down the drain. While the stuff may seem slippery to you at room temperature, certified master plumber Elisha French, owner of Texas Plumbing Solutions, LLC, says that it is often a source of major drain clogs. When olive oil cools—like when it comes in contact with cold water or is left to sit in an uninsulated pipe—it can solidify, causing a blockage in no time.


white woman spooning flour into sieve

Surprisingly enough, something as simple as flour can cause a messy plumbing problem before you know it. According to French, flour can clump together when water hits it, seriously clogging your drain and potentially requiring a professional to remedy the situation.

Coffee Grounds

coffee grounds in coffee filter
Shutterstock / Nor Gal

While dumping a cup of coffee down the drain likely won't cause any harm, allowing those coffee grounds to go with it can cause serious trouble. Dawson says that coffee grounds "can accumulate in pipes and cause clogs," potentially leading to an expensive repair in your future. And for more essential advice from plumbers, learn 21 Ways You're Damaging Your Home, According to Your Plumber.

Animal Fat

bacon cooking in a cast iron skillet
Shutterstock/Elena Elisseeva

Although you might be tempted to rinse that greasy pan right after cooking some bacon, sausage, or steak, doing so can cause serious plumbing issues down the line.

"The problem is that the water and grease cool as [they] move through the pipes and solidify, attracting other debris and creating a blockage," explains Arizona-based plumber Mark Stevens with Forrest Anderson Plumbing and Air Conditioning. Instead, he recommends pouring the grease into a can or jar, allowing it to cool, and then disposing of it in the trash can.


white plate on wooden table with chicken bones on it
Shutterstock/Zhou Eka

While it may feel like you can dump virtually anything into your garbage disposal, bones can quickly gum up the works, according to French. Not only can they dull your disposal's blades or get completely stuck, but bones are also often accompanied by animal fat that can congeal in the drain.

Mashed Potatoes

silver pot with mashed potatoes and potato masher
Shutterstock/Joe Gough

Viscous foods like mashed potatoes may separate easily enough when water hits them, but that doesn't mean you can safely use your sink to dispose of them. According to Dawson, starchy foods like mashed potatoes can cause significant plumbing clogs, meaning you're better off tossing them in the trash, leaving as little to be rinsed down the drain as possible. And for more mistakes to avoid at home, here are 17 Ways You're Ruining Your House, According to Electricians.

Banana Peels

bananas in metal sink
Shutterstock/Phraram Creation

They may be soft, but your garbage disposal is not adept at getting rid of banana peels. Dawson warns that banana peels and other starchy foods can "develop into a paste that slows down the blades" of your average disposal, as well as potentially clogging pipes along the way.

Fibrous Vegetables

washing celery in sink
Shutterstock/Ahanov Michael

Last night's veggie side can cause serious problems for your home's plumbing if you're not careful. According to Dawson, "celery, asparagus and other fibrous vegetables … can tangle around blades" in your average garbage disposal, leaving you with an expensive repair on your hands.

Egg Shells

egg shells and bowl in sink
Shutterstock/Andrii A

They may seem easy enough to crack, but egg shells can cause a surprisingly big problem if you toss them into the sink. According to Dawson, egg shells are the culprit behind many plumbing issues, as they can pack together when combined with water and create clogs. And for more useful information delivered straight to your inbox, sign up for our daily newsletter.


pouring liquid medicine into spoon

Have some extra medicine on your hands? Whatever you do, don't pour it down the drain. While it may not clog your pipes, there are even greater risks involved—according to the United States Geological Survey, over 4,000 types of prescription medication make their way into our environment, polluting groundwater and soil, and harming or even killing livestock and wildlife along the way. Instead, the EPA recommends returning unused medicine to drug take-back locations, like certain pharmacies, or mixing them with substances like coffee grounds or cat litter, sealing them in a container, and disposing of them in the trash.


red gas cans on garage shelf

If you've got some extra gasoline in your basement or garage, make sure to check out your city or town's hazardous waste disposal options—and whatever you do, don't pour it down your drain. According to the Agency for Toxic Substances and Disease Registry, gasoline can contaminate groundwater, and even inhaling small amounts of gasoline fumes can cause major problems. In fact, in 2017, 42 children and two adults in Rockville, Maryland had to be evaluated by first responders or hospitalized after becoming nauseated by a small amount of gasoline trapped in a nearby storm drain.


white man holding white pesticide container over lawn

Those pesticides may be keeping your garden bug-free, but they're doing no favors to the environment—especially when you dispose of them in the sink. The EPA cautions against pouring any type of pesticide down the drain, as your average municipal water treatment facility may not have the equipment necessary to completely filter them out of the water supply, and pesticides can potentially harm both humans and animals if consumed.

Sarah Crow
Sarah Crow is a senior editor at Eat This, Not That!, where she focuses on celebrity news and health coverage. Read more
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