Are Coffee Grounds Safe for Septic System Tanks?

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Septic systems are not designed to be used as garbage disposal to process food waste or scraps. Coffee grounds, food scraps and other items that will not break down in the septic tank can even cause problems and clogging.  

As we’ve discussed here, a healthy septic system needs a balanced ecosystem of healthy bacteria that break down waste products. The bacteria feed off of human waste.

coffee filters and septic system
If you have a septic tank, coffee grounds & filters should go in the trash – or the compost pile.

Ground coffee beans on the other hand, while they do break down eventually if composted in the ground, will not dissolve in your septic tank and even if you are using a septic tank activator those enzymes will not dissolve coffee grounds. 

So the short answer is: NO, do NOT put coffee grounds down your drain if you live on a property with a septic system. The coffee will not dissolve in the tank. Adding solids, like ground coffee, to your septic system will just lead to having your tank pumped more often which will cost you money. A better solution is to compost coffee grounds, use them in your garden or if no other option is available – throw them away along with the paper filter (if you use one).

(Actually plumping experts explain that you really shouldn’t put them down the drain on a city sewer system either).

Why you should not put coffee grounds in your septic tank:

Non-decomposed solids that fail to break down will fall to the bottom of the tank and create a layer of a semi-solid slug. This layer has to be pumped by a professional and hauled away. It may seem like an insignificant amount but it does add up…even if you just make one pot of coffee a day, over the course of time that ends up being pounds and pounds of grounds that will sit at the bottom of your septic tank.

The grounds will just add the volume of solids and increase the frequency you’ll need to get your tank pumped. You’ll basically be paying to have it pumped out and hauled away- so don’t put it down the drain in the first place!

Better solutions for getting rid of coffee grounds if you have a septic tank: 

coffee grounds
Coffee grounds. Image Credit: Max Pixel

Instead of throwing your used coffee grounds down the drain, there are better and more environmentally friendly ways to toss your coffee.  If you do any gardening or even just have houseplants, there are several very practical uses for used coffee grounds. Compost: Over time, coffee grounds do break down in a compost pile and are great for compost.

EPICA Stainless Steel Compost Bin 1.3 Gallon-Includes Charcoal Filter
Composting bin we use under our sink (Click to see on Amazon)

Keep in mind that contrary to what many people think (because of its brown color) spent coffee is actually considered a “green” element in a compost pile. While fresh coffee is acidic, used coffee grounds are actually 2% nitrogen and with a carbon/nitrogen ratio of about 20 parts carbon to one part nitrogen, they are “Green” and will need to be mixed with “brown” material (paper, cardboard, etc). 

One simple way to compost while keeping your kitchen odor-free is to get a simple stainless steel composting pail that either sits under your sink or on your kitchen counter. It takes the hassle out of composting and is a good solution for keeping coffee grounds out of your septic system.

What About Paper Coffee Filters?

paper coffee filters
Paper coffee filters don’t do well in a septic tank. Image Credit

Although coffee filters have the look and feel of being thin, almost similar to toilet paper, some people think that they will break down in water as tissue would. However, appearance can be deceiving. Most coffee filters are made with 100-gram paper which is too thick and heavy to break down sufficiently in your septic tank.

The filters are more likely to clog up the lint filter on your tank which will mean either taking off the riser lid from your tank and having to reach in to clean it manually or calling a maintenance service to clean the obstruction for you. In the end, it will be either an unpleasant experience, expensive or both!

Camco RV Bathroom Toilet Tissue - 4 Rolls Sewer-Safe, Septic-Safe, Biodegradable 1-Ply Bath Tissue Designed For Trailer, Motorhome, & Marine Sanitation Systems (40275)
Single Ply Septic Safe Toilet Paper

The best solution is to not use your septic system as a garbage disposal, food waste including coffee grounds and food scraps should be thrown in the garbage or composted when practical (coffee grounds, veggie peels, etc). Actually, for years we were told not to even use a garbage disposal on a septic system, but things have changed-click here to see your options.

Coffee filters can also be composted. If you do not compost then the only other practical option is to throw them out. The same is true for other household paper products like paper towel, paper napkins, and tissue.

Speaking of paper, you can also do your septic system a favor by using a thinner, one-ply toilet paper which will break down easier than standard 2-ply.

This short video is a quick example of the difference between single-ply and 2 ply toilet paper and how it breaks down much quicker.  We have not found the Majesta EZ toilet paper in our area, but you may be able to find it in natural food stores or larger supermarkets. There are also other RV and Camping toilet papers.

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