May 26, 2025, 9:37 am | Read time: 2 minutes
For owners of espresso machines, it’s possible for coffee grounds to end up in the drain after brewing. This can also happen when washing coffee pots and cups. But should this be a problem? After all, the coffee grounds are washed away with the next rinse water—right?
For many, the day begins with the aroma of freshly brewed coffee. Espresso lovers, in particular, appreciate using an espresso machine—including the typical knocking out of the grounds. But where should the used coffee grounds go? In many households, the coffee grounds end up in the sink and thus in the drain. But is that really sensible? Or can coffee grounds in the drain become a problem?
Coffee Grounds in the Drain
In many households, not only food scraps but also coffee grounds end up in the drain. But is that a problem? We asked around. “The coffee grounds settle in the siphon when there’s no movement, just like in the cup or coffee filter,” says Frank Ebisch from the Central Association for Sanitation, Heating, and Air Conditioning (ZVSHK). Once the coffee grounds have settled, it’s hard to mobilize them.
However, if it’s just a few crumbs, as is usually the case when washing cups and pots, it shouldn’t be a problem. “The grounds are carried away with the next rinse water,” the expert says. How effectively the coffee grounds are carried away depends on the flow rate and the amount of water.
Although small amounts of coffee grounds don’t pose a problem for the drain, you should avoid disposing of larger quantities down the drain. “If larger amounts accumulate, a professional from the sanitation, heating, and air conditioning field will need to clear the drain,” Ebisch advises.
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Where Should You Dispose of Coffee Grounds?
Many people dispose of used coffee grounds on the compost in the garden. Others use coffee grounds as fertilizer, hoping to provide nutrients to plants in the garden or on the balcony. This assumption is not entirely wrong. Indeed, small amounts of dry coffee grounds can be beneficial on calcareous soils. If you want to use coffee grounds as fertilizer, you should apply them specifically—and in small amounts—as they change the soil’s pH value.
One argument against disposing of coffee grounds on the compost is their antibacterial effect, which can negatively impact the microorganisms in the compost. Additionally, coffee grounds can clump and hinder the decomposition process. On the other hand, the grounds can also help by enriching the compost with nutrients and serving as food for earthworms. However, you should ensure that the coffee grounds are added to the compost without a filter bag, as these decompose very slowly.