Our household drains are cunning things; agents of deception, really. They act as magic portals to rinse our messes away, and once we’ve dispatched something down the sink or toilet, we rarely think of it again. Bad us! Because in reality there are many things we pour down the drain that can cause mayhem in household pipes, septic systems or municipal sewer plants — and in turn can be especially vexing for water ecosystems and their inhabitants. Water treatment facilities can remove many contaminants, but a lot of deleterious chemicals and substances still end up in our rivers, lakes and oceans.

So for the sake of healthy plumbing and healthier water habitats, here are some of the more common contenders for things that you shouldn’t send down your pipes.

1. Coffee grounds: Some people seem confident that coffee grounds down the drain will not present a problem; most plumbers disagree, saying that nothing causes more blockages than coffee grounds and grease. Plus, this: 20 ways to reuse coffee grounds and tea leaves.

2. Eggshells: Even with a garbage disposal, eggshells create granular waste that loves to hook up with other waste to form clogs.

Grease, fats and oils: Any of these slimy threesome can mix with other nasty things and clog household pipes to form “fatbergs” that block sewers. So gross. Grease, fat and oil buildups caused about 47 percent of the up to 36,000 sewer overflows that happen annually in the United States.

3. Grease: Including cooked and/or melted fat from meat, bacon, sausage, poultry, skin from boiled poultry, and even gravy.

4. Fats: Including meat trimmings, uncooked poultry skin, cheese, ice cream, butter, milk and other dairy, nut butters, shortening and lard.

5. Oils: Including cooking oil, olive oil, salad dressings, condiments and mayonnaise.

Produce stickersLittle produce stickers cause problems if they're rinsed down the drain. (Photo: Twin Design/Shutterstock)

6. Produce stickers: Believe it or not, the tiny plastic-containing identification stickers on fruits and vegetables are regularly washed down the drain and create problems. They can get stuck in your drain and pipes as well as stuck on wastewater treatment plant pumps and hoses, or get caught in screens and filters. And if they get past all that, they end up in the water.

7. Flushable cat litter: Flushing “flushable” cat litter presents two problems. One is that cat feces can harbor the parasite Toxoplasma gondii, which lives in cat feces and causes the disease toxoplasmosis. It's not destroyed during water treatment and is a threat to marine species, especially sea otters. Part two: Flushable cat litter clogs drains and is a mess for septic systems.

8. Condoms: It’s not like latex will disintegrate in water. Your condoms will live a long and illustrious life in the sewer and many will escape for a life at sea. Nobody wants to see your condoms and marine life doesn’t want to choke on them, so throw them in the trash. Thank you.

9. Paper towels: Although they may be biodegradable, the absorbency inherent in paper towels makes them perfect for clogging up pipes. Instead of flushing them, compost them or switch to cloth kitchen towels.

10. Cotton balls: Same as above.

Flushable wet wioesEven wet wipes that claim flushability are a disaster for water treatment plants. (Photo: BeautyBlowFlow)

11. Flushable wipes: Notes the New York Times in an article about New York City’s $18 million expenditure on wet wipe-related equipment problems: “Often, the wipes combine with other materials, like congealed grease, to create a sort of superknot.” Wet wipes do not disintegrate like toilet paper does and they cause no end of chaos for sewer systems and water treatment facilities across the country.

12. Paint: Most municipalities have different requirements for both latex and oil paint. Some are so strict that even rinse water from brushes used with water-based paints should not be poured down the drain. Oil paint almost always needs to be disposed of at a hazardous waste facility.

13. Conventional cleaning products: Phosphates, antibacterial agents and other assorted compounds make conventional cleaning products disruptive to water ecosystems. Avoid the mess and harm by using all-natural cleaners or concoct your own cleaners from your kitchen.

14. Car fluids: Keep motor oil, transmission fluids, anti-freeze and other automotive chemicals away from pipes, including household and storm drains, in order to protect our waterways.

15. Medications: Studies have found everything from ibuprofen and antidepressants to birth control hormones in our natural waterways. Much of that comes from human urine, but an estimated one-third of medication sold in the U.S. is left unconsumed. Rather than flush old medicine down the toilet, as was once advised, it’s much better to drop it off with a medication take-back program if there’s one nearby, or you can mix it with something unpalatable like coffee grounds sealed in a plastic bag and place it in the trash.