What to Do If You Accidentally Throw Rice Down the Drain
If rice ends up in your drain, act quickly to minimize potential damage. Avoid adding more water to the sink, as this can exacerbate the problem by causing the rice to swell further. If the rice has just been disposed of and hasn’t caused a blockage yet, flush the drain with a large volume of water to try to push the grains through the system before they expand.

You can also try a combination of vinegar and baking soda to break down the starches in the rice. Pour half a cup of baking soda followed by half a cup of vinegar down the drain, then after 15 minutes, flush with hot water. If the blockage persists or if you notice slow drainage, it’s wise to call a professional plumber. It’s better to address clogs early before they require major intervention.