According to Mayor Bill de Blasio, there are only four things that should go in your toilet.

The city launched a new public service announcement about a problem in the city sewers.

They’re called “fatbergs,” which are masses of clumped grease and personal hygiene products - such as “flushable” wipes, paper towels, cooking grease and tampons.

Cooking grease can cling to the inside of pipes and sewers and block them completely, causing flooding and sewer backups.

The city says if a product is labeled “flushable” it generally means it will clear the toilet bowl.

The city spends about $18.8 million a year to decrease sewers.

The city is urging residents to place anything other than “the four p’s” in the trash. "The four p's" are paper, poop, pee and puke.

Did you know about fatbergs?