What’s Recyclable and Compostable?

A conversation on the do’s and don’ts for what you put in your bin

Staff | TPIN
Denver's recycling, trash and compost carts

I’m standing in front of three different bins – trash, recycle and compost – with a goopy container of peanut butter in my hands.

  • How clean does it have to be?
  • It’s plastic – does that mean it can go in the recycling bin?
  • What about the lid – keep it on the container or separate it in the recycle bin…or just throw it away?

If you are like me, some days it feels like you need an advanced degree to get recycling right.

So, I sat down with the head of Denver’s Recycling and Composting program to glean the do’s and don’ts so I (and you) can be an All-Star recycler.

Nina Warsdorf is the Waste Diversion and Recycling Manager for the City and County of Denver. So, if anyone can help us, she can!

Note – what’s recyclable and compostable depends a lot on where you live. But a lot of what we talk about is true for many communities across the Front Range, especially around what can’t be recycled.

What's Recyclable and Compostable in Denver?

Check out my full conversation with Nina Waysdorf, Denver’s Waste Diversion and Recycling Manager.

All Things Composting

What are the changes to Denver’s Compost and Recycling?

In 2022, Denver’s combined recycling and composting rate was 26%. That’s better than the statewide rate of 16% but still not that great.

That’s a problem because that means nearly ¾’s of the city’s waste is just going right to the landfill, where it rots releasing methane pollution (a greenhouse gas 28 times more potent than carbon dioxide) and forcing us to mine, drill, and log for new virgin materials instead of reusing the glass, aluminum and paper we already have.

Nothing that can be recycled or reused should wind up in a landfill wasting away.

Many people don’t realize that nearly 50% of what winds up in our trash cans is organic matter (leaves, eggshells, bones, orange peels) and could be composted.
What is compost? It’s basically dirt. But really high-quality dirt. It contains nutrients that our gardens, parks and farmlands need.

We know the single easiest way to ensure people recycle and compost is if they have a bin that gets picked up from their curb (every week ideally).

If you live in Denver, that’s exactly what’s going to happen.

If you are in a single-family home or a multifamily unit serviced by the city (generally six units or less), you may have noticed your curbside purple recycling bin is now getting picked up every week.

In addition, everyone will be getting curbside, green, composting bins.

As of April, 30,000 Denver households already had curbside composting. Starting in July, an additional 150,000 households will receive curbside composting services, rolled out in phases based on collection districts. They’ll take months to add each new district so they can ensure the rollout is smooth and to give time to educate people on composting.

What’s the timeline for your area? You can find that information here.

You’ll also get some flyers when it’s coming.

What can be composted in Denver?

Food scraps and yard waste.

That includes meat, dairy, bones, eggshells, banana peels, apple cores, orange rinds.

It also includes the leftovers that went bad.

You can also put weeds, leaves, dead plants, grass clippings and branches (make sure they are cut down to the right size…no tree trunks) in the compost bin.

Can compostable cups, bowls and napkins go in the Denver compost bin?

Unfortunately, cups, bowls, napkins and other products that are not food scraps or yard waste cannot go in the compost bin even if they indicate they are compostable.

This may be news to you.

If you were like me, you’ve been putting these green and sustainable products in your compost bin for awhile – not just in Denver but if you live in Boulder, Longmont and other composting cities.

However, the facility that is in charge of taking what we put in our green compost bins and processing it into the high-quality dirt that becomes compost, was seeing way too much contamination from things that can’t be composted. That could result in dirt filled with broken up plastic pieces – not something any gardener or farmer wants to amend into their soil.

A big reason for this contamination is that many of us buy products that seem compostable – they may have words like “sustainable” or eco-friendly,” or they may literally be the color green, which to me means compostable.

But unless it has been designed with the right ingredients that can decompose in a composting facility, it just contaminates other compostable materials.

One solution – truth in labeling for compostable products so if it says it’s compostable it truly is compostable. That will reduce mistakes from consumers like you and me and reduce contamination so compost facilities have the confidence to accept them without undermining the quality of the compost they produce.

Good news! We passed a bill that will do exactly that. Starting January 1, 2024, SB23-253 prohibits companies from using labels, color schemes or images that would mislead a consumer into thinking a product is compostable when it is not.

Ideally this helps us get back to a point where Denver’s compost system can take those compostable bowls, cups, and other products because compost facilities will have more confidence that only compostable items will be in the compost bins.

Which bags should I put my compost in?

The one exception to the food scraps and yard waste composting principle are green compost bags.

You can (and should) put your compost in compostable bags. They need to be 3 gallons or less. And you should look for the “CMA certified” label – that means it’s a product that has been certified to break down by the Compost Manufacturers Alliance.

You can find a list here.

How do I avoid stinky or buggy compost?

I’ve been a part of the Denver curbside compost program for a few years. But when I first signed up, I was worried about the stench and the bugs, especially with the pail they give you to put your compost in.

But a few years in, I’ve got few complaints. The design of the pail ensures there is decent air flow and the smells you may expect are no more a problem than when you put food in your trash can.

Remember – this is the same stinky stuff you had before – you are just putting it in a different bin.

And just like your trash, take it out every few days and you are fine.

But Nina had some additional tips:

  • Put your compost in the freezer. No smells. And when it’s full, put it in your curbside green cart and it will be thawed by the time it reaches the facility.
  • You can also layer food scraps and yard waste – that helps reduce bugs.
Household compost bin with food scraps Staff | TPIN
A compost cart with yard waster and food scraps Staff | TPIN
[Composting] It’s a win-win. We’re reducing our landfill waste but we’re also helping our soils and our gardens and our farms, so it really is an easy way for people to take action individually. Nina Waysdorf
Waste Diversion and Recycling Manager, City and County of Denver

How to Be a Master Recycler

So, let’s talk about recycling.

It can be hard to know what goes in the recycling bin.

What does it even mean to be recyclable?

Ultimately, something can be recycled if it has value – someone is willing to buy it to turn it into something else – and we have the ability to collect it, sort it and transport it to them.

  • Some items are just going to get burned or trashed – that’s not recyclable.
  • Some items are too small and we can’t effectively collect or sort them – that’s not recyclable.
  • Some items are made of a material that can’t be turned into something else – that’s not recyclable.

What can be recycled in Denver?

The top recyclable materials

Aluminum cans, glass, tin and steel cans (including empty aerosols), cardboard boxes, paper products, junk mail, paper boards (think cereal boxes) are all recyclable.

Which plastics can be recycled in Denver?

When it comes to plastics, containers are the best – think bottles, tubs, jugs and jars. Nina advises not to worry about the triangle chasing symbols with numbers in the middle and just ask yourself – is this a container. If it is, drop it in the recycling bin.

But even plastics that can be recycled have a limited lifespan. Materials like glass and aluminum can be recycled more times in their lifespan.

Which plastics can’t be recycled in Denver?

Don’t put plastic utensils, bags, shrink wrap/packaging or that soft/brittle plastic that is commonly referred to as styrofoam in your recycling bin. It doesn’t matter what its plastic number is.

It’s particularly important you don’t put single-use bags in the recycling bin because they can jam the sorting machines and drive up the costs of the whole recycling system.

Let me say that again – don’t put your recyclables in a plastic bag and then put that in the recycling bin.

No plastic bags!

Typically, you can’t recycle plastics that are malleable as well – think a toothpaste tube.

For any of these non-recyclables, the best thing to do is to avoid them up front with reusable items or items that can be recycled. But if you do have these non-recyclables, put them in the trash.

Putting non-recyclables in the recycling bin threatens to push good recyclables into the landfill because they get contaminated by the things that can’t be recycled.

How clean does something need to be before it’s recycled?

Empty but not spotless.

Water is a precious resource, so you don’t need to use it to make sure something is completely spick and span. The recycling process can get at any remaining residues.

I think of it as a goop test. This container will be bumping around with a bunch of other containers in a truck. If it’s goopy and stuff leaks out, it will make a mess of the other items and could lead to them ALL being landfilled.

So think “goop free.”

Do I need to empty my soda bottle before recycling it?

Yes. Do not put a bottle in the recycling bin with soda or any other liquid in it. That liquid will leak out and could ruin the other recyclables it’s mixed in with.

Do I put caps or bottle tops in the recycling bin?

They are too small on their own to get recycled. So if they are loose – toss them in the trash.

If they are still on the bottle (make sure the bottle does NOT have any liquid) then you can leave them on and put the bottle in the recycling bin.

One caveat is that if the lid is made from a different material than the bottle, it’s best to separate them and toss the cap or top. Remember – this stuff is getting sorted and so metal and plastic won’t go to the same facility. So remove the tops and toss them.

Can I recycle junk mail?

Yes. Even if the mail has the see through plastic pieces. And even if they have a staple or two.

Can I put shredded paper in the recycling bin?

No. Remember – this stuff needs to get sorted. It’s impossible to separate all the littles shreds of paper once they get mixed in with everything else.

Keep shredded paper or small scraps of paper out of the recycling bin.

Can I put electronics in the recycling bin?

No. In fact, it’s illegal to put electronics in the landfill in Colorado because many of them contain hazardous materials. They also contain a lot of valuable material we can and should reuse.

Click here for details on how you can schedule a hazardous waste pick-up and what items are eligible.

Can I put batteries in the recycling bin?
Can I put fluorescent bulbs in the recycling bin?

No. But they are an item you can schedule to have collected.

Click here for details on how you can schedule a hard to recycle waste pick-up.

Can I put paint or paint thinners in the recycle bin?

No. But you can find a place to drop off your leftover paint for free using this site locator.

They can also be collected if you schedule a hard to recycle waste pick-up.

Can I put plastic bags in the recycling bin?

No. Not only can they not be recycled but they can get caught in the sorting machines at recycling facilities and jam the machines shutting down the whole facility.

Can I put polystyrene in the recycling bin?

No. It’s not a great material for recycling.

Can I recycle pizza boxes if they are greasy?

Pizza boxes are valuable recyclables because they are made out of cardboard, which can be collected and turned into something else relatively effectively.

However, it needs to be empty (no pizza or chunks of cheese caked on the box or leftover dipping sauce containers bouncing around).

A little bit of grease is fine (a few spots). If the box is soaked, you’ll need to throw it away, though I offer two tips.

  • If it’s only the bottom of the box that is soaked, cut off the top and recycle it.
  • If you have composting services, you may be able to compost it (though not in Denver right now – check with your service provider).
The biggest contamination we see is plastic bags. All the time….Plastic bags we can never take in our recycling bins. Styrofoam too is another big contaminant that we see. We just can’t, just don’t recycle Styrofoam. It’s really not a good material for recycling. Nina Waysdorf
Waste Diversion and Recycling Manager, City and County of Denver
Single-use plastic bag Staff | TPIN
Single-use plastic bags and polystyrene cups and containers Staff | TPIN

Final tips from Denver’s recycling director

Denver has a number of resources for people who may be scratching their head standing over their recycling bin.

Remember – know before you throw!

We want to do the right thing and sometimes it feels like erroring on the side of putting it in the bin is the right thing.

But it’s most important that we put the right things in the bins.

And with this blog, and the resources above, we can all be recycling all-stars.

You should know before you throw….We want to recycle, we want to compost as much as we can but it’s more important to do it right and to just recycle and compost the things that actually do go into those bins. Nina Waysdorf
Waste Diversion and Recycling Manager, City and County of Denver

What’s the future of recycling and composting in Colorado?

Under the leadership of Governor Jared Polis and legislative zero waste champions like Senator Lisa Cutter, Colorado has a suite of nation-leading policies that should help Denverites and recyclers across the state improve our recycling rates and reduce waste.

We called out a number of these policies in our 2023 State of Recycling and Composting in Colorado report including:

  • The Plastic Pollution Reduction Act – Starting January 1, 2024, single-use plastic bags and polystyrene containers will be phased out, reducing a major source of non-recyclable waste.
  • Truth in Labeling for Compostables – Beginning January 1, 2024, companies will be prohibited in using colors, images and labels to mislead consumers into thinking a product is compostable when it is not. Over time, this should help compost facilities expand the products they can accept and we as consumers can put in our compost bins.
  • Producer Responsibility – The Joint Budget Committee will need to approve the next step of Colorado’s producer responsibility program. Once implemented, it will require producers of paper and packaging (cans, jars, boxes, etc.) who sell these products in Colorado to take responsibility for the end-of-life of these materials by funding recycling services for all Colorado residents, including those with historically limited access such as people living in apartments and rural areas, and reimburse local governments that already run these programs. It will also provide Coloradans with a clear list of materials that can be recycled statewide.
  • Right to Repair – Beginning January 1, 2024, farmers and ranchers will have access to the tools, parts and software they need to repair their equipment. This victory follows on the heels of a similar Colorado bill that extends these protections to people in wheelchairs. Nationally, other states have passed Right to Repair policies around consumer electronics, helping to reduce electronic waste.

These policies taken together with cities like Denver that are expanding access to recycling and composting could vault Colorado up from being one of the worst states when it comes to waste reduction and diversion to one of the best.

PIRG Right To Repair Campaign Director Kevin O’Reilly (FAR LEFT) and CoPIRG Director Danny Katz (SECOND RIGHT) watch as Colorado Gov. Jared Polis signs agricultural Right To Repair into law. @COSenDem on Twitter | Public Domain
CoPIRG Executive Director Danny Katz rallies with supporters in front of the capitol to call for strong legislative action to curb plastic waste. Staff | TPIN
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Danny Katz

Executive Director, CoPIRG Foundation

Danny has been the director of CoPIRG for over a decade. Danny co-authored a groundbreaking report on the state’s transit, walking and biking needs and is a co-author of the annual “State of Recycling” report. He also helped write a 2016 Denver initiative to create a public matching campaign finance program and led the early effort to eliminate predatory payday loans in Colorado. Danny serves on the Colorado Department of Transportation's (CDOT) Efficiency and Accountability Committee, CDOT's Transit and Rail Advisory Committee, RTD's Reimagine Advisory Committee, the Denver Moves Everyone Think Tank, and the I-70 Collaborative Effort. Danny lobbies federal, state and local elected officials on transportation electrification, multimodal transportation, zero waste, consumer protection and public health issues. He appears frequently in local media outlets and is active in a number of coalitions. He resides in Denver with his family, where he enjoys biking and skiing, the neighborhood food scene and raising chickens.

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