It okay to let some food run down the drain, but a lot of it expands when mixed with water and can lead to a block. Pasta and rice are two foods to watch out for. Also, pasta is made with flour, which will become sticky and catch other things in your pipes.
The only paper product that should go down your drain is toilet paper. It has been specially designed to break down and disintegrate in water. Always dispose of other paper products such as paper towels, cotton balls, and feminine hygiene products in the trash. These items are extremely absorbent and will easily clog your pipes.
Even though most cleaning products are liquid, they should never be poured down the drain because they contain harmful chemicals. Many contain phosphates, antibacterial agents, and other compounds that aren’t removed at the water treatment plant and can be hazardous to the ecosystem.
You might think that a crushed up eggshell will go down the drain smoothly, but it actually is causing a blockage. The sharp, hard edges of the shell will collect other things coming down your drain and eventually cause a clog.