Quick answer: No, you shouldn’t pour coffee grounds down the sink or garbage disposal. Grounds don’t dissolve in water; they settle in pipes, bind with grease and build up into a dense sludge that can clog the drain. Throw them in the trash or compost instead, and if a drain is already blocked, try a plunger, then clean the P-trap.
Rinsing coffee grounds into the sink is tempting, especially after a French press. Here is what happens to them in your pipes, how to clear a clog they cause, and better ways to get rid of them.
In this guide 4 sections
What happens when you pour coffee grounds down the drain?
You may have heard that coffee grounds are “good” for your pipes. They aren’t.
Plumbers commonly list coffee grounds alongside grease as things that should never go down a kitchen drain.
The reason coffee grounds can clog drains is that coffee grounds are usually very fine, especially if you brew espresso.
These fine particles can stick to grease and other material already in your drain.
Over time the coffee grounds will build up layers of sludge almost like cement. Coffee grounds don’t dissolve in water, so they don’t simply wash away.
A few stray grounds rinsed from a mug, followed by plenty of water, are unlikely to cause trouble in clean pipes. The problem is making a habit of it.
If your pipes are older or your sink already drains slowly, don’t pour any grounds down it: they will add to the build-up and can block the drain completely.
Can you put coffee grounds in a garbage disposal?
No, even if you have a garbage disposal you should not put coffee grounds down it. The drain and pipes attached to your garbage disposal are susceptible to getting clogged just like a regular drain.
Just like in a regular drain the coffee grounds will eventually form a thick paste that cannot be washed away.
A disposal chops food into smaller pieces, but coffee grounds are already tiny, so it does nothing to help them through the pipes.
Wet coffee grounds clump together and settle rather than flowing away.
How do you unclog a drain clogged with coffee grounds?
Luckily it is relatively simple to clear your pipes if they are clogged by coffee grounds. You can actually save money by fixing the problem yourself instead of hiring an expensive plumber to do the work.
Chemical drain cleaners are designed to break down grease, hair and other organic clogs; packed coffee grounds are better removed mechanically, so start with the methods below.
Here are some things you can try to unclog your drain that has been clogged by coffee grounds.
Use a plunger on your sink
If you have a plunger at home you can use it on your sink. Plungers aren’t just for toilets!
To do this method, your sink has to be clogged to the point where water will not flow through the drain.
Fill the sink with water so the drain hole is submerged by the water. If you have multiple connected drains you should plug your other drain holes. You can do this with a rubber stopper, or any towel or waterproof material that can make a waterproof seal.
Now, vertically hold the plunger above the affected drain, and cover the drain hole, making sure it’s fully covered by your plunger. It’s important to try to get a seal to get the full effect of your plunger. Plunge the sink by pushing your plunger down and then pulling up with the suction multiple times. Continue doing this until the sink drains the water quickly.
Clearing your sink’s P-trap
Most clogs in your sink occur in the P-trap.
This is the U-shaped piece of pipe under your sink. This is the second method you can try if plunging your sink does not work.
The first step to this method is locating the P-trap. Most likely your grounds will be located in a U-shaped pipe right under your sink basin. Once you find it place a bucket to catch any water or spills that may happen.
Once you have the section of pipe you want to remove look for nuts that you can loosen that connect it to the drain and to your sink. You may need a wrench to loosen these nuts. If you have plastic pipes you should be able to do this with your hands.
Once this piece of pipe is disconnected, inspect the inside and try to remove anything blocking the flow of water.
Afterwards, just reverse the steps and put your P-trap back together!
Use a drain snake to loosen compacted coffee grounds
If plunging and cleaning the P-trap don’t work, use a drain snake (also called a drain auger). Hardware stores sell inexpensive hand snakes, and many also rent powered ones.
A drain snake is a long, flexible cable that you feed into the drain. Push it in until you feel resistance, then turn it to break up the blockage.
If none of these clears the drain, call a plumber.
How should you dispose of coffee grounds?
Instead of pouring your coffee grounds down the sink you can actually use them for a lot of different things around the house. They have many practical uses and can even go into a homemade coffee scrub.
If you are interested in some creative ways to use your coffee grounds click here to read our article on 20 creative uses for coffee grounds.
Otherwise, add them to a compost bin or put them in the trash. If you brew with a French press, scrape the grounds out with a spoon or spatula before rinsing the carafe.
Usually you can just dump your coffee grounds into the trash, but in some special cases you may want a small container with a lid to toss your coffee grounds in.
These cases are if you have pets or are afraid of mold.
Coffee grounds are toxic to pets and if your pet has the tendency of getting into your trash you should get a small container with a lid that you can toss your coffee grounds into. Read why pets should not have coffee at this article.
As for the mold, coffee grounds get moldy extremely easily, and if you are sensitive to spores in the air you will want to have a special covered container for your coffee grounds.
Frequently asked questions
Are coffee grounds good for your pipes?
No. The idea that coffee grounds clean or deodorize pipes is a myth. They don’t dissolve, and they can collect with grease into a clog.
Is it OK to rinse a few coffee grounds down the sink?
A small amount rinsed from a cup with plenty of water is unlikely to cause problems in clear pipes. Regularly dumping grounds from a coffee maker or French press is what leads to clogs.
Can you put coffee grounds in the toilet?
It’s best not to. Grounds behave the same way in toilet and sewer pipes as in a sink drain, so the trash or compost is the safer choice.
Are coffee grounds dangerous for pets?
Yes, used grounds still contain caffeine, which is harmful to dogs and cats. Keep them in a lidded container if your pet raids the trash; see why dogs shouldn’t have coffee.