Why Audit

Disposal records indicate how much waste an organization or community generates; determining what that waste contains requires a physical audit. Composition — not tonnage alone — informs the decisions that follow: program design, service and contract structure, and the claims a report can support.

Waste audits are generally undertaken to answer some combination of five questions: what is being generated, and in what quantity; how much of it could have been diverted; how effectively existing diversion programs capture material; what contamination is present in diversion streams; and whether a given intervention produced measurable change. The sections below outline four principal drivers for conducting an audit.

The scale of the problem

The two countries measure differently — Canada reports disposal from all sources surveyed; the U.S. reports municipal solid waste — so each is most meaningfully compared against its own trend line rather than directly against the other. In both countries, diversion rates have remained below one-third.

Composition of disposed waste

Composition data from both countries illustrate the scale of remaining diversion potential. In Metro Vancouver, where organics have been banned from disposal since 2015, compostable organics remain the largest single component of disposed garbage. In the United States, food is likewise the largest component of landfilled municipal solid waste. Grouped by available diversion pathway, roughly half or more of disposed material could in principle have been diverted.

National and regional averages provide context rather than site-specific answers. Individual audits routinely find compositions that differ substantially from these figures — office buildings dominated by paper fibre, food retail by organics, manufacturers by film plastics and wood packaging. This variation between the average and the individual stream is the central rationale for site-specific measurement.

Driver 1 · Regulatory compliance

In some jurisdictions, waste audits are not optional — and the two countries get there by different routes.

Canada. Waste is provincially regulated, and Ontario is the clearest audit mandate on the continent: under O. Reg. 102/94 (the "3Rs Regulations"), designated industrial, commercial and institutional establishments must conduct a waste audit, prepare a waste reduction work plan, and update both every year, retaining records for the Ministry on request. The companion regulation O. Reg. 103/94 requires the same establishments to operate source-separation programs for designated materials. Elsewhere, audits are pulled in by provincial and regional instruments — Metro Vancouver's organics disposal ban, Quebec's residual materials management plans and organics strategy, Nova Scotia's long-standing disposal bans — which all create material streams somebody has to measure.

United States. There is no federal audit mandate; the drivers are state and municipal. California's SB 1383 requires organics diversion of essentially every generator, and AB 341 mandates commercial recycling; Massachusetts bans commercial food waste from disposal above a weekly threshold; Vermont's Act 148 phased in universal recycling and an organics ban; and cities including New York, Seattle and Austin add commercial recycling and organics ordinances. Although none of these instruments mandates audits explicitly, demonstrating compliance — and evaluating program performance under them — generally depends on composition data.

Driver 2 · Cost control

Disposal invoices capture only a portion of the total cost of waste. Costs not itemized on the invoice include hauling charges for underutilized container capacity, the purchase value of goods discarded unused, internal handling labour, and forgone rebates and avoided fees associated with diversion. Audit data allow these components to be quantified.

Driver 3 · Program performance

Once any diversion program exists, two audit-only metrics govern it. Capture rate — of the material that could have gone in the blue bin, how much did? — tells you whether the program is reaching people. Contamination rate — how much of what's in the blue bin shouldn't be? — tells you whether it's reaching them correctly, and it directly affects processing fees and load rejections. Neither metric can be derived from bin counts or hauler reports; both require composition data. The formulas and worked examples appear in §09 Analysis.

Driver 4 · Commitments you have to prove

Zero-waste certifications set diversion bars (90% is the common benchmark) that must be demonstrated with data. Municipal councils adopt diversion targets that staff must report against. Corporate ESG disclosures increasingly include waste intensity metrics. Each of these commitments ultimately rests on measured composition data, supported by methodology sufficient to withstand external review.

The audit cycle

A single audit establishes a baseline. Much of its value is realized on subsequent passes: with methodology, categories, and season held constant, differences between audits can be attributed with reasonable confidence to the interventions made between them.

Scope and limitations