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Can Coffee Grounds Really Go Down the Drain?

Posted on November 12, 2025 by Melbourne Plumber

Clogs make up a large portion of calls plumbers receive. People will try various little tricks to try and get the liquid flowing in their drain or toilet and when that doesn’t work, they call in the professionals.

Many clogs are simply due to people flushing things down the toilet or drain that don’t belong there. Because they have always done so or because they grew up watching a family member do it, they assume it’s fine for the plumbing system. Nothing could be further from the truth.

One substance which a large percentage of people think is ok to wash down their sink drain is coffee grounds. I guess the thinking is that since they are made of up of thousands of tiny particles that they will wash away easily. But people who use a French Press understand that this isn’t the case. That’s because when you press coffee in a French Press the grounds will often get lodged at the bottom after all the liquid has been removed.

This same effect is happening in your drains. Sadly, many of the people who do end up dumping coffee grounds down the drain are French Press users. This is because the grounds are not surrounded by a filter. The grounds in the filter typically get thrown away in one felt swoop.

Water flow in pipes relies on smooth surfaces. Coffee grounds increase friction and turbulence, leading to sediment buildup. Plumbers report clogs forming in as little as a few months with regular dumping, especially in older homes with narrower pipes.

Instead of putting your coffee grounds down the sink you should simply scoop them into the trash can. In fact, you should scoop all debris and cook material into the trash before washing dishes in the sink or dishwasher.

Flushing cooking oil or grease down your kitchen sink is a major no-no as well. This stuff will harden at some point in your drain. Now picture all the gunk it will latch onto when it starts to harden. Coffee grounds and animal fat make for a horrific clog. A clog which is deep down your drain line can be very labor-intensive and costly to clear.

The smart rule of thumb is to scrape your plates directly into your trash can and to dispose of grease in the same way. Your kitchen sink and plumbing are not designed to handle debris and oily grease. These combinations are a ticking time bomb for your plumbing system.