A recent WRAP survey found that three-quarters of UK residents are “confused” about what materials they can put in the recycling bin. “Not me,” you scoff — you savvy reader of planet-friendly publications. But a quick look in your recycle bin may reveal items that aren’t recyclable at all.

In the best case scenario, your non-recyclable rubbish will end up in landfill. In the worst case, you’ll slow down the works of the whole recycling plant. Keep the system running smoothly by cutting these four items out of your bin — and perhaps your life.

Black Plastic: The Invisibility Cloak of Recycling Plants

You may feel a little guilty about the number of ready meals you polish off every week. But at least those plastic trays are recyclable — right?

Unfortunately, if your trays are black, your local recycling plant probably can’t accept them.

The reason for this is pretty technical. Although the plastic is recyclable, the sensors at an automatic sorting facility can’t “see” black. This black plastic ends up getting pushed along the conveyor belt with the rest of the non-recyclable rubbish.

A handful of retailers, including Marks & Spencer, are experimenting with pigments that won’t confuse the sensors. But careful recyclers should avoid black plastic until those alternatives hit the shelves. After all, do you really need another frozen lasagne?

Juice and Milk Cartons: Don’t Judge a Box by Its Cover

On the surface, a milk carton has a lot in common with your typical recyclable cereal box. But imagine what would happen if you poured milk into that cereal box: you’d get a drippy, soggy mess.

Cartons are lined with a layer of watertight plastic to protect you from that sticky scenario.

The paper part can be recycled, but many recycling plants don’t have the technology to peel away the plastic. If your local plant doesn’t accept cartons, check out the Carton Council. This is an effort that TetraPak and other top carton manufacturers created to connect consumers with recyclers.

If you can’t find a service in your area, you can send your cartons to Terracycle, a company that fills in the gaps left by council recycling efforts.

Coffee Pods: The Rubix Cube of Waste

A typical coffee pod is made of four materials: plastic, aluminium foil, paper, and coffee grounds.

Separating these materials into their respective waste streams can be a perplexing puzzle. This effort is one that manufacturers and third-party companies are only beginning to solve.

Nespresso offers a free mail-in recycling service for their pods, and Terracycle offers a similar service for all other brands.

If you prefer a DIY method, you can separate the pieces yourself using a cup-cutting tool. Of course, the best way to cut coffee pods from the waste stream is to avoid using them all together. Nearly every other coffee-making process, from the Aeropress to the French press, produces nothing more than easily-compostable (or reusable) coffee grounds.

Soiled Takeaway Boxes: All Greased up and Nowhere to Go

While most cardboard is fully recyclable, its lifespan ends as soon as it meets pizza grease and other oily residue.

If a grease-stained box enters the paper-making process, it can cause a layer of oil to form on top of the fiber pulp and gum up the whole process.

A handful of UK restaurants use compostable boxes that help solve the soiled cardboard conundrum, including Feng Sushi and Clerkenwell Kitchen, but the trend has yet to spread to low-end takeaway shops.

This could be a good excuse to reduce your intake of pizza and other takeaways. If it’s greasy enough to ruin cardboard forever, it’s probably not great for your body.

Managing your household waste is a lot like managing your diet. Both boil down to savvy shopping, careful choices, and understanding all the options.

For more information on how to send less to the landfill — and eat healthier while you’re at it — check out our ultimate guide to reducing food waste.