March 4, 2026, 10:46 am | Read time: 3 minutes
Many people routinely pour coffee grounds down the drain after breakfast. After all, they are fine, organic, and seem harmless at first glance. A little water afterward, and everything is gone. Is that a mistake? myHOMEBOOK asked an expert how harmful coffee grounds really are for the drain.
A freshly brewed coffee smells wonderful and is also a morning pick-me-up. To elevate the enjoyment in their own kitchen, coffee lovers get an espresso machine. However, every household appliance has its quirks. When knocking out the coffee grounds, the question arises: Where to put the grounds? In many households, the coffee grounds end up in the sink and thus in the drain.
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. “The coffee grounds settle in the siphon when still, just like in the cup or coffee filter,” answers Frank Ebisch from the Central Association for Sanitation, Heating, and Air Conditioning (ZVSHK). Once the coffee grounds have settled, it is difficult 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 transported away with the next rinse water,” says the expert. How effectively the coffee grounds are carried away depends on the flow rate and the amount of water.
Although small amounts of coffee grounds do not pose a problem for the drain, one should refrain from disposing of larger quantities down the drain. “If larger amounts accumulate, a plumbing professional will need to come and clear the drain,” informs Ebisch.
Where Should You Dispose of Coffee Grounds?
Many dispose of used coffee grounds on the compost heap 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 useful 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 level.
The antibacterial effect of coffee grounds, which can negatively affect microorganisms in the compost, speaks against disposal 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 to add the coffee grounds without the filter bag to the compost, as these decompose very slowly.