Can Coffee Grounds Go Down the Sink? (Really?)

We always throw our brewed coffee grounds into the compost bucket, but if you don’t make compost or want to put wet grounds into the garbage, then can you simply put them down the sink?

It’s not safe to dump coffee grounds down the sink even with the faucet running, because coffee grounds don’t break down in water and will form into clumps that will block the drain.

Let’s dive down into the topic of putting coffee grounds down the sink in greater detail, and discover why this is a bad idea and what you should do instead (if you don’t want to end up with a plumber’s bill)…

Can Coffee Grounds Go Down the Sink?

Is It Safe to Dump Coffee Grounds Down the Sink & Drain?

It’s tempting to simply pour your used grounds down the sink when you wash your French press or wipe down your machine – please don’t, because it’s not safe to dump coffee grounds down the drain.

Why can’t coffee grounds simply be swilled down the plug hole? It’s because coffee grounds don’t break down in water, so after they’ve been rinsed down the sink, they reform into clumps. These could eventually cause blockages.

It’s far better (and still pretty easy) to dump your used coffee grounds in the compost, where they’ll help to enrich it. You can even scatter them straight onto the soil as a fertilizer.

Can Coffee Grounds Go Down a Waste Disposal Unit?

Coffee grounds can’t go down the waste disposal unit (or garburator) for the same reason that they can’t go straight down the drain: they’ll simply form a clump again.

The grounds won’t dissolve and they can’t break down further in the garburator, so they’ll just end up clogging the disposal unit and drains. If the garburator gets clogged, you’ll soon notice the unpleasant odor and see soiled water back up into your sink.

How Do I Prevent Coffee Grounds From Going Down the Drain?

If you use a filter, you can simply empty the whole thing into the compost, because most filters are biodegradable.

This means that the used coffee grounds are disposed of easily, and you can simply rinse or wipe down the filter basket (and the remaining grounds will be minimal). You can do the same with a portafilter. 

What about something like a French press, which needs a proper cleaning after brewing coffee? Use something like a flexible spatula or even a wodge of paper towels to wipe out the used coffee grounds, straight into the compost or garbage.

This should mean that there are minimal remaining grounds going into the drain when you wash up the press. If there are a quite a few left behind, fill the jug with water and swirl it around, then pour it straight onto the soil.

To make extra sure, a stainless steel mesh strainer over the plug hole can help to trap larger particles of coffee or anything else.

How Do I Unclog Coffee Grounds From the Sink?

What do you do if coffee grounds have accidentally gone down the plug hole? There are a few things you can try.

Make a baking soda and white vinegar solution, which you pour down the plug hole. Put the plug in to make sure the mix moves downwards. After about an hour, remove the plug and pour boiling water down the drain. If it doesn’t work, try again.

You can also try plunging the sink. If you have two plug holes, seal one, and plunge vigorously. This can get things moving again, but isn’t a permanent solution because the coffee grounds are still there. You’ll need to call for a professional to finish the job.

Then, there’s the plumber’s snake approach. Unless you’re a pro, you probably don’t have one of these in your shed or garage, but you can rent them. We’d actually suggest renting the plumber along with the snake, as this is a pretty tricky job.

This film shows how plumbers use a snake to clear a drain that’s been blocked with coffee grounds.

As you can see, it’s not a straightforward task. Once the drain has been unclogged, make up a sign and fix it above the sink: Do not pour coffee grounds down the sink!!!

What Dissolves Coffee Grounds? (Will Drano Dissolve Coffee Grounds?)

Coffee grounds can be dissolved, but it’s not an easy (or safe) process. Yes, Drano will dissolve the coffee grounds, but as you may know, Drano dissolves everything, and if you use a harsh chemical, you may end up damaging the drainage system.

If it’s that badly clogged, we’d suggest you call in a pro rather than risk doing this yourself.

This must happen frequently in coffee shops, right, so what do they use? You can get an alkaline powder (which is basically what baking soda is) called Cafiza.

This is what coffee shop employees use to clean down the machines after use. It works by breaking down and softening the grounds, and will eventually dissolve them.

Is Cafiza safe to use? Compared with Drano, most certainly! Just mind your eyes, and it’s a good idea to use gloves. 

You could also try a homemade version, using baking soda. As we mentioned earlier, if you have a blocked drain, make a baking soda solution, pour it down the sink, then after an hour, flush it through with boiled water.

Can You Flush Coffee Grounds Down the Toilet?

No, you certainly can’t flush coffee grounds down the toilet. This is for the same reason that you can’t pour used coffee grounds down your kitchen sink: they’ll clog the drains.

Coffee grounds behave exactly the same in the drainage system, no matter what route they took to get down there. They don’t dissolve in water, so will re-clump after being flushed, eventually causing clogging and even blockages.

We can understand the thinking here: sinks take liquid while toilets take, er, solid objects. Let’s be frank here: poop dissolves, coffee grounds don’t.

How Do You Stop Coffee Grounds Going Down The Sink?
How Do You Stop Coffee Grounds Going Down The Sink?

Can Coffee Grounds Go Down the Shower Drain?

No, coffee grounds can’t go down the shower drain. At first, this sounds like a strange question: why would I be standing in the shower, with used coffee grounds?

Well, actually, coffee grounds make an excellent body scrub or even shampoo, and this is a great way to re-use them.

But, now we also know that coffee grounds shouldn’t enter the drainage system, by any route. How do we prevent our homemade body scrub from clogging the shower drain?

Well, firstly, we’re talking about far smaller quantities of grounds here. You can use a mesh cover over the plug to pick up any stray grounds. Besides, body scrubs always seem to land all over the tiles rather than drain away neatly, so you can wipe them off when you’ve finished.

(If you like the idea of a coffee body scrub, try this DIY recipe.) 🙂