If you’ve made French Press coffee before then you’ve likely wondered what the best method is for disposing of the coffee grounds. You may have considered washing them down the drain or simply throwing them in the trash.

This article shares the best (and worst) ways to get rid of your French Press grounds daily.

How do you dispose of French Press coffee grounds?

The most useful ways to dispose of French Press grounds are by using them as a fertilizer in your garden or potted houseplants, as a skincare exfoliant, fridge deodorant or composting medium. Otherwise, it’s best to simply throw them in the trash because they will clog your sink plumbing system.

Use coffee grounds as fertilizer in your garden or houseplants

Spent coffee grounds from your freshly brewed French Press can be mixed into potting soil used to grow houseplant or in your garden. This is because the organic grounds promote microorganism growth and improve water drainage.

Fresh and composted spent coffee grounds were proven to stimulate plant growth when added to lettuce soil, according to a study conducted by the School of Agriculture at Mountain Research Centre^[2].

Another study from Porto University proved that spent coffee grounds increase a plant’s chlorophyll production by 61% as long as the coffee made up less than 10% of the soil^[1].

Use them as a body scrub

Spent coffee grounds have proven to be excellent exfoliants. Meaning, they can be used as part of a skincare routine to clean away dead skin cells that might otherwise clog pores and cause acne.

The reason for this is because spent coffee grounds are the organic remains of the coffee bean that did not dissolve in water. Their rigid and fine grain size make them a great tool for exfoliation.

Studies have also shown that the caffeic acid found in coffee has antioxidizing properties that protect skin from sunlight^[5]. This adds another reason for using your coffee grounds as part of your cosmetic routine.

Spent coffee grounds can be composted into useful plant substrate

A study by the Nova Scotia Agricultural College discovered that spent coffee grounds are an effective material to use in composting systems^[4]. Coffee grounds composted using three different composting methods showed increased levels of nitrogen, phosphorus and potassium. These are important macronutrients required for healthy plant growth.

However, the study discovered that earthworm growth and survival suffered when coffee was used as the sole composting material. It seems as if coffee most effectively composted when combined with other soils and organic materials.

Use French Press coffee grounds as a refrigerator deodorant

Another great use for your spent French Press coffee grounds is to put them in an open container at the back of your refrigerator. The grounds will absorb odors and keep your fridge smelling fresh.

A study from the Vietnam Journal of Science and Technology demonstrates that coffee can even eliminate strong food odors, such as onion^[3].

Make your own coffee scented candles

The creative folks out there can even consider using their coffee grounds as an ingredient when making coffee-scented candles. This is a very economical way to get multiple uses out of your coffee bean budget.

Throw them in the trash

Another option is to simply discard your spent coffee grounds in your trash bin. This might be the easiest and safest option available to you if you do not have houseplants or a garden, do not intend on face scrubbing and do not compost.

Can you dispose of coffee grounds down the sink?

Plumbers suggest that coffee grounds are one of most frequent causes of drainage clogs. Spent coffee grounds are mostly insoluble because the soluble compounds have already been dissolved into your beverage.

As a result, coffee grounds will get caught in small spaces and cling to grease and oil that also makes its way into your sink plumbing system. After enough time this may cause blockages.

How do you get coffee grounds unstuck from the bottom of a French Press?

Simply dumping coffee grounds into the trash bin can be tricky because the grounds get stuck to the bottom of your French Press carafe. This is especially true for French Press grounds because they have been compacted using the coffee maker’s plunger.

All you need to do is remove the plunger, add a small amount of water from your tap, swirl the spent grounds and water around a little and then pour the slurry into the strainer. From here it’s easy to dump the grounds from the strainer into the trash bin.

You can also buy mesh strainers that fit into your sink’s drain.

References

1. Cruz, R., Baptista, P., Cunha, S., Pereira, J. A., & Casal, S. (2012). Carotenoids of lettuce (Lactuca sativa L.) grown on soil enriched with spent coffee grounds. Molecules, 17(2), 1535-1547.
2. Gomes, T., Pereira, J. A., Ramalhosa, E., Casal, S., & Baptista, P. (2014). Effect of fresh and composted spent coffee grounds on lettuce growth, photosynthetic pigments and mineral composition. In VII Congreso Ibérico de Agroingeniería y Ciencias Horticolas (pp. 1-5). SECH e SEAgIng.
3. Huong, B. M. (2019). ANTI-ODOUR TREATMENT ON 100% WOOL FABRIC USING COLORANTS FROM COFFEE GROUND RESIDUES. Vietnam Journal of Science and Technology, 57(3A), 77-77.
4. Liu, K., & Price, G. W. (2011). Evaluation of three composting systems for the management of spent coffee grounds. Bioresource technology, 102(17), 7966-7974.
5. Yamada, Y., Yasui, H., & Sakurai, H. (2006). Suppressive effect of caffeic acid and its derivatives on the generation of UVA‐induced reactive oxygen species in the skin of hairless mice and pharmacokinetic analysis on organ distribution of caffeic acid in ddY mice. Photochemistry and photobiology, 82(6), 1668-1676.