How to do a household waste audit–and why
A waste audit is an analysis of a localized waste stream from your building, household, classroom, town or business. It can identify what types of waste that local generates, and how much. How do you conduct an audit? What can you learn from one?
Steps in a waste audit
- Find the edges of your study. Choose a timeframe and a location for your audit: your entire house for a week; two main trash cans on campus sampled twice a week for a month; all the trash at work one one day. What will give you the clearest picture of that waste stream? If your waste stream is variable (trash on Saturdays looks very different than trash on Mondays), consider a week-long survey. This will also determine what you leave out– most audits look only at solid waste, but skip over carbon waste, sanitary waste, and other waste streams. Generally, you want to keep the date of your audit a secret if you’re auditing a workplace or campus so people don’t change their behaviours and affect your data.
- Collect that waste! Gather the waste within your designated time frame and location. If you are interested in temporal patterns and flows in waste (which days or activities produce the most waste), label your collection with the date and time collected. If you just want to create a “snapshot” of what exists in your waste stream, you can gather your waste all together. Make sure waste is clean or frozen if you are not collecting and counting on the same day.
- Categorize and count your waste. How you categorize your waste depends on what you are looking for. Do you only care about recyclables versus non-recyclables? Then those are the only two categories you need. What about compostable waste? Or plastics? IF you want to compare your waste to your city’s waste, then use the categories used by your city’s sanitation system. Some of these categories are reflected in the worksheets below. The most common categories are: paper & cardboard, glass, plastics (including rubber), textiles, wood, metal, compostable, special/hazardous waste. Often these categories are broken down into recyclable and non-recyclable types.
You also have to choose how to “count” your waste. Most will do weight and/or item numbers.
Waste collection worksheets:
- New Jersey Waste Audit worksheet for grades 5-6 (original location)
- Minnesota Office of Environmental Assistance, K-6 Waste Management Education Curriculum (original location)
EPA Solid Waste Audit Form (excel sheet)
University of North Carolina at Chapel Hill, How to Perform a University Waste Audit (power point) (original location)
- Waste Audit and Consultancy Services, Step-by-Step Waste Audit
Analysis of your waste audit
What does your count mean? What you can learn from your waste audit is dependant on what you collected and how you collected it, so make sure you know what you want before you design your collection procedure. These are some of the questions you can potentially answer with a waste audit:
- What is the largest category of what you throw away?
- Where do the items in that category come from? Is their origin something you can influence to reduce our waste?
- How much of your waste is preventable, and how much is not? Can you actually prevent the preventable portion of your waste? How?
- How much of your waste could be diverted from the trash to other destinations, like recycling, composting, or reuse? Would the biggest category in your audit be impacted by diversion?
- How is your waste different from your city’s waste stream (see their annual reports)? Why?
- How is your waste specific to your local place and culture?
- Where in your building, town, campus, etc, is the most trash created? Why? Can that be changed?
- If you do an audit before and after a policy or behaviour change, you can use it to see if your intervention is working.
Household waste is only part of municipal solid waste (MSW), which also includes commercial, institutional, and construction and demolition waste. Municipal solid waste, in turn, is only a tiny fraction of all waste produced, the vast majority of which is industrial solid waste (ISW). This means that when you do a waste audit, you are not analyzing waste in general, but a very particular genre of waste at a specific location, so your findings may not generalize to wider issues in waste, or may only generalize to your particular genre of waste in similar contexts.
What have you used your waste audit for?