What Can Go in a Denver Compost Bin Under A1 Organics Rules?
- Ethan Babil
- Aug 16
- 3 min read
A1 Organics, which processes most Denver commercial organics, accepts food scraps and yard and plant trimmings only. The sole permitted liner is a 3-gallon compostable bag certified by the Compost Manufacturing Alliance. No paper, no packaging, no compostable serviceware, no plastic, glass, or metal.
Two of those exclusions catch nearly everyone: paper products and certified compostable serviceware. This post gives you the full accepted and rejected lists, explains why the serviceware rule exists, and covers what happens when a load gets contaminated.
What is accepted?
Category | Examples |
Produce | Fruit and vegetable scraps, peels, trim, spoiled produce |
Protein | Meat, poultry, fish, bones, shellfish shells |
Dairy | Cheese, butter, spoiled milk solids |
Grains | Bread, pasta, rice, tortillas, baked goods |
Beverage residue | Coffee grounds, loose tea |
Other food | Eggshells, sauces, cooking scraps |
Yard material | Grass, leaves, plant trimmings, small branches |
If it grew and it is food, it almost certainly qualifies.
What is rejected?
Category | Examples |
Paper | Napkins, paper towels, pizza boxes, coffee filters, paper plates |
Compostable serviceware | Cups, lids, clamshells, cutlery, straws, even certified items |
Plastic | Bags, wrap, produce stickers, gloves, utensils |
Glass and metal | Bottles, cans, foil, jar lids |
Liquids | Bulk liquid waste, grease, cooking oil |
Other | Pet waste, diapers, treated wood, ash |
Why are compostable containers rejected?
Because certification and reality diverged.
A1 Organics stopped accepting packaging and serviceware to control contamination. The core problem is that "compostable" certification reflects laboratory conditions, and material that breaks down in a controlled lab environment frequently does not break down in field composting conditions on the timeline of an actual commercial operation.
The result was a stream full of intact plastic-looking fragments that had to be screened out by hand or sent to landfill anyway.
So the rule is simple, if inconvenient: certified compostable serviceware goes in the trash in Denver. It is still a defensible purchasing decision for other reasons. It is not a composting decision.
What bags are allowed?
Only 3-gallon compostable bags certified by the Compost Manufacturing Alliance (CMA).
Not any compostable bag. Not any size. CMA-certified, 3-gallon.
The reason is field testing. CMA certification is based on how material actually performs in commercial composting facilities rather than lab conditions, which is why it survived the packaging purge when other certifications did not.
If a bag is not CMA-certified, either use loose scraps or use a permitted bag. There is no third option that keeps the load clean.
What happens when a load is contaminated?
Contaminated loads get rejected, downgraded, or landfilled, and the cost comes back to the generator through contamination fees or service changes.
At scale, contamination is the single largest threat to a composting program's economics. It is also almost entirely a signage, placement, and training problem, which means it is solvable without capital.
What are the top contamination sources in practice?
Plastic bags used as liners
"Compostable" cups and clamshells
Paper towels and napkins
Produce stickers
Nitrile glove fragments from prep lines
Notice how many of those come from staff acting in good faith. Nobody is sabotaging your compost. They are guessing, and the guess is wrong.
Frequently asked questions
Can I compost pizza boxes in Denver? No. Paper products including pizza boxes are not accepted in the commercial organics stream.
Are coffee filters compostable in Denver? Coffee grounds are accepted. The filter is not.
Can I use a regular trash bag if I take it out immediately? No. Plastic film is a primary contaminant. Use loose scraps or a 3-gallon CMA-certified bag.
Are compostable cups really not allowed? Correct. Certified compostable serviceware is not accepted in Denver's commercial organics stream.
Do these rules change my URCO obligation? No. Your obligation is to provide compliant organics service. These rules determine what can go into it without wrecking the load.
Build signage your team will actually follow
Melly's Recycling is a Denver URCO compliance company, not a hauler. Our signage and education materials are built directly against current accepted-materials rules, in English and Spanish, so your staff and residents stop guessing. We also handle Waste Diversion Plans, gallons-based capacity analysis, annual reporting, and documentation, and we coordinate licensed Denver haulers through a sealed-bid process.
You finish what you started.
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