How to Compost

Composting is a biological process that breaks down organic material (like food scraps and yard trimmings) and recycles them into a beneficial, nutrient-rich soil amendment. There are different processes and methods, all which combine microbial life, water, air, and possibly heat. The City and County of Denver’s compostable materials are processed by A1 Organics and undergo a windrow composting process. The finished compost product repairs soil structure and builds entire microbial communities. Aside from vital and diverse nutrients for your soil and plants, compost also improves water retention by up to 5x. This means less water is needed, less money spent, and a healthier ecosystem is established.

In addition to the benefits of the finished compost product, composting organic material helps to reduce our impact on the environment and mitigate climate change. Organic material in a landfill releases methane, a powerful greenhouse gas. By diverting that material to the composting process instead, we allow microorganisms to break it down and produce a beneficial product, putting material back into the soil.

Learn more about A1’s process here!

If it isn’t food scraps or yard & plant trimmings it doesn’t go in your curbside compost cart. Here are some common materials that are NOT allowed in the compost cart:

Paper products: including tissues, paper towels and napkins, tissue paper, brightly colored paper, paper scraps and shredded paper, tea bags, and coffee filters (please put coffee grounds into compost cart and trash the filter), pizza boxes.

All compostable packaging and products: even those that are certified compostable, including cups, utensils, plates and takeout containers.

Compostable bags: except 3-gallon or smaller CMA certified compost bags.

Paper Yard Waste Bags: except April-June and September-November.

NO plastics, glass, metals, diapers, pet waste (even in compostable bags), treated wood, rubberbands, twist ties, produce stickers, sod, mulch, or dirt are accepted in the compost cart.

Beginning July, delivery of compost carts will be phased in by neighborhood starting with Solid Waste Collection District 2, which includes City Park, City Park West, Clayton, Cole, Elyria-Swansea, Five Points, North Capitol Hill, Skyland, Whittier, and parts of Globeville.  Once compost service is rolled out out in SWC District 2, DOTI will move on to SWC District 4, which includes residents in Montbello, Gateway, and Green Valley Ranch. The department is prioritizing neighborhoods with lower diversion rates in its rollout, and is developing a rollout schedule for the remaining districts.

Gradually phasing in our weekly compost service will allow us to better educate and coordinate with residents, mitigate contamination, and allow our collection routes to grow with the service. At this time, no action is needed from residents and they'll continue to receive the Phased Service Roll-out Credit on their invoice until we deliver their green cart. We will reach out directly to residents within each neighborhood before their service begins with resources to help them prepare.

Existing customers will not see any changes in their service. If you are a current compost customer or not filling up your trash cart on a weekly basis, you can downsize your cart. If you are not a current compost customer, we recommend waiting until you receive your compost cart before downsizing your trash cart so you can know what size you need.

Residents can request smaller or larger carts at any time through their Denver Utilities Online account, Denvergov, or by calling 311. As compost service is phased in, residents are encouraged to utilize the Cherry Creek Recycling Drop-Off, which is open for all food scraps and yard trimmings accepted for compost collection.

There are multiple reasons. For every certified compostable product (such as cutlery, tableware, cups, straws, and compostable bags) you might come across, there are several more “look-alikes” that mislead the public into thinking these items are compostable by using vague terms like “biodegradable” or “plant based" when in truth they often contain non-compostable plastics.

Unfortunately, the volume of contamination A1 receives due to misleading labeling makes any packaging or serviceware items too costly to accept because of the challenge to distinguish and sort certified compostables from “look-alike” products that are not compostable.

If you choose to buy compostable bags to use in your kitchen pail or green carte, please make sure you purchase the right bags.  All bags used for organics must carry the official CMA (Compost Manufacturers Alliances) Logo. The CMA logo lets our drivers and processor know that products with this label have been tested to ensure that they will compost quickly, completely, and safely. Certified compostable bags may be purchased online and at some grocery stores.

Learn what bags are accepted here.

Compost loads will be rejected by A1, the City’s compost processor, and sent to the landfill at the expense of the city, increasing methane emissions at the landfill. For this reason, our drivers will NOT be picking up any compost loads deemed too contaminated to pass inspection at A1.

The city will also conduct cart audits compost carts regularly to continue to educate residents on what goes in their carts.

The organics stream (aka compost) is not the same as the recycling stream. At a recycling plant, human sorters see contaminants like plastic bags and pull them off the sorting line by hand. Automatic equipment such as screens and optical sorters help separate materials. In comparison, by the time compostable materials arrive at a compost facility, they are already a gooey mess. Imagine pulling plastic stickers off of rotten banana peels, or even pulling plastic bags off of decaying material. A certain degree of contamination in sorted recycled products is allowable with recycling markets. Compost is not so lenient. Small pieces of plastic, glass, or aluminum will remain in the finished compost product. Farmers, gardeners, and other compost buyers need the clean, nutrient-dense food scraps and yard trimmings. But they don’t want to grow our food using compost contaminated with glass, plastic, and metals.

The best way to keep your carts free from contamination is to ensure that your carts are properly stored between collections.

Review the cart storage and set-out guidelines here.

As we roll out compost, we encourage residents who want to get started early or have extra yard debris to take advantage of the FREE Cherry Creek Recycling Drop-Off. All items that can composted in the curbside collection are accepted at the Drop-off during operating hours. 

Vermicomposting (using worms) and backyard composting systems are easy to use alternatives and produce high quality compost.  You can set these up at home or with community members in shared gardens!  Watch an informative video and learn the steps to amazing compost here.

Use reusables whenever possible. The switch to reusable shopping bags has become the norm. Keep the reuse habit going—bring your reusable mug to a coffee shop, stash a reusable set of silverware and a napkin in your bag or car for easy access on-the-go, and bring your own reusable to-go containers for leftovers. Skip the stuff and say no to disposable items like plastic cutlery and condiment packets.

Support reuse businesses. Have your to-go meal packed in DeliverZero reusable containers when ordering from participating restaurants. Reuse service companies are on the rise, with more companies no doubt coming online soon, so encourage your favorite restaurant to join a reuse program to help switch the default away from single-use disposables of any kind, regardless of whether they are recyclable, compostable or trash. 

Know before you throw. Become a Zero Waste sorting pro. Check the Waste Directory to see if your to-go container is recyclable. Do not recycle “compostable” to-go containers. 

Learn more tips and tricks for waste reduction and reuse here.