The Four Waste Categories: A Beginner's Guide

Most cities sort household waste into four streams. Knowing them is the first step to sorting correctly at home.

Waste sorting looks different from country to country, but a four-stream model has become the global default: recyclables, hazardous waste, kitchen (wet) waste, and other (residual) waste. Each stream flows to a different destination — recycling, safe treatment, composting, or energy recovery — so putting an item in the right bin matters.

BlueRecyclables

Recyclables are materials that can be recovered and remade: paper and cardboard, plastics, glass, metals, and clean textiles. Before tossing them in, empty, rinse, and flatten them. A greasy pizza box or a dirty plastic tub can contaminate a whole batch, so when in doubt, keep it clean or move it to other waste.

RedHazardous Waste

Hazardous waste contains substances that harm health or the environment: batteries, fluorescent tubes, expired medicine, paint, and chemicals. These must go to a dedicated collection point — never into the regular bin — because heavy metals and toxins can leach into soil and water if landfilled or burned.

GreenKitchen (Wet) Waste

Kitchen waste is any perishable organic material: leftovers, fruit and vegetable peels, tea leaves, and garden trimmings. Drain off excess water and remove plastic bags so it can be composted or processed into biogas. Keeping it separate sharply reduces odour and landfill volume.

GreyOther (Residual) Waste

Other waste is everything that is not recyclable, hazardous, or kitchen waste — contaminated cups, cigarette butts, ceramics, and hygiene products. It is usually sent to incineration with energy recovery or sanitary landfill, so the goal is to keep this stream as small as possible.

Quick Tips for Daily Sorting

• Keep two bins at home (one for recyclables, one for kitchen waste) to make sorting a habit.
• When unsure about an item, look it up instead of guessing — a wrong item can spoil a whole load.
• Buy less, reuse more, and choose simple packaging to shrink the "other" stream at the source.

Helpful Tools

Try our Garbage Search to check which category an item belongs to, the Carbon Calculator to estimate the CO₂ you save by recycling, and the Sorting Quiz to test your knowledge. For a worldwide comparison, see Global Standards.

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