Can sugar clog kitchen drains?

In the morning, I often have coffee with sugar remaining in my cup that I want to dump.

Does pouring it down the kitchen drain create a possible problem of the sugar “clumping” and over time, maybe creating a drain blockage?

[PS–there must be a specific term for this “clumping”–what is it?]

Sugar is pretty soluble, so unless you’re dumping a cup of sugar down the drain there won’t be any blockage. I think the worst case scenario is if the sugar gets stuck in a clog and dissolves slowly because there isn’t much water flowing past.

A few teaspoons per day should be no trouble.

Unless you never put anything else down that drain it’s not going to be an issue. If it still worries you run a little hot water after you dump the coffee cup.

I am constantly amazed by the things people worry about.

That worries me…

One possibility could be that the sugar would encourage biofilm/biomass growth which would clog the drain, but this would require enough water to sufficiently dissolve at least some, if not all, of the sugar in which case it would most likely flow on down the drain, but it could happen.


Sugar is water soluble, and sugar solubility increases with the temperature of the water. I am surprised if any sugar you put in your coffee is not completely dissolved by the time you are down to the bottom of your cup. Even if you dump a cup of sugar right into the drain it will dissolve and rinse though with some water.

Sugar is the least of your worries. The biggest problem for drains is saturated fats, like bacon grease, that might go down liquified but congeal at lower temperatures, and mechanical blockers like eggshells or other insoluble particles.