How to classify your waste: EWC codes, mirror entries and hazardous waste

Every load of waste needs a code before it can be moved, transferred or received — and getting that code right decides whether the waste is treated as hazardous. This guide explains how the European Waste Catalogue is structured, how to find the right six-digit code, and how to handle mirror entries where you have to assess the hazard yourself.

How do I classify my waste?

The European Waste Catalogue — known in the UK as the List of Waste (LoW) — is the single classification everyone in the chain uses. The producer assigns the code, and it then travels with the waste on the transfer note or consignment note and into the receiver's records. Classifying correctly is a legal duty: the code determines how the waste must be stored, carried, described and, ultimately, disposed of or recovered.

What is the structure of an EWC code?

The catalogue is hierarchical, so you always drill down in the same order — pick the chapter first, because the same material can sit under different codes depending on the activity that produced it. The table below shows how the three levels nest for one worked example:

A few widely used entries show the range: 17 01 01 is concrete, 17 09 04 is mixed construction and demolition waste, and 20 03 01 is mixed municipal (household-type) waste. Each is a full six-digit code — never record just the chapter or sub-chapter.

How do I find the right EWC code?

DEFRA's guidance sets out the order to work through:

• →Start with the source. Chapters 01–12 and 17–20 are grouped by the industry or activity that generated the waste — pick the one that matches how your waste arose.
• →Narrow to the sub-chapter and entry. Read down to the most specific six-digit code. Prefer a precise entry over a catch-all.
• →Fall back to chapters 13–15 or 16 (oils, packaging, absorbents, or wastes not otherwise specified) only if the source-based chapters do not contain a suitable entry.
• →Check for an asterisk. If the entry you land on is marked *, the waste is hazardous. If it is a mirror entry, you have an assessment to do (below).

The List of Waste contains 842 EWC codes, of which 408 are hazardous — identified by an asterisk (*) after the six-digit code.

What makes an EWC code hazardous?

The asterisk is the signal, but it does not always mean "always hazardous". Entries fall into two kinds:

• →Absolute entries — a single code that is always hazardous (marked *) or always non-hazardous, with no assessment required. The catalogue has already made the decision.
• →Mirror entries — a paired hazardous / non-hazardous choice for the same kind of waste, where you must assess the specific waste to decide which code applies.

What is a mirror entry and how do I assess it?

Mirror entries exist because the same waste stream can be clean in one situation and contaminated in another. To classify it you need to know what dangerous substances the waste contains and in what concentration, then test that against the hazardous-property thresholds. The HP properties describe what makes a waste dangerous:

Work out what is in the waste (from safety data sheets, the process, or testing), convert those substances to their hazardous concentrations, and compare against the HP thresholds. If any property is triggered, use the hazardous (*) code from the pair; if none is, use the non-hazardous code. DEFRA's WM3 technical guidance is the reference for carrying out this assessment.

What should I do when I'm not sure of the classification?

Misclassifying is a compliance risk on both sides: recording a hazardous waste as non-hazardous can breach duty of care and hazardous waste controls, while over-classifying adds unnecessary cost. Practical steps when a code is unclear:

• →Confirm the producing activity — the same material can have different codes depending on where it came from.
• →For a mirror entry, base the decision on the waste's actual composition, not on the code that is cheapest to record.
• →Keep the evidence — safety data sheets, test results and your reasoning — so the classification can be justified later.
• →Where composition is genuinely uncertain, obtain a competent hazardous waste assessment or check with the Environment Agency, SEPA, NRW or the NIEA.

This guide is general information about waste classification, not legal advice. Classify against the primary sources below and, where the hazard status is unclear, seek a competent assessment or check with your environmental regulator.