Case Study

Residential Curbside Recycling


On average, each American generates roughly 4.48 pounds of waste per day.  Although the recycling rate has increased over the years, the current rate of 35.2% still lags behind most developed countries.1 The contamination rate (generated when non-recyclable materials are comingled beyond sorting capabilities) is roughly 25% and the standard rate for rejection can be as low as 0.5%.2 High contamination rates increase the cost to process recyclables and reduce the quality of recyclables able to enter the commodity market.3


Two inefficiencies in residential curbside recycling programs are missed opportunities and contamination.  Missed opportunities occur when items that could be recycled are instead thrown in the trash. On the flip side, contamination occurs when prohibited, non-recyclable materials are placed in recycling containers. Both missed opportunities and contamination have behavioral components that can be targeted with interventions.

Barriers and Solutions

Missed opportunities arise from barriers that deter people from trying to recycle, whereas contamination arises from barriers that prevent people from recycling correctly.  Barriers include:

  • Lacking the knowledge required to recycle correctly.
  • Having little extrinsic motivation to recycle consistently or correctly.
  • Having little intrinsic motivation to recycle consistently or correctly.
  • Preferring to continue current behavior, whatever it is.
  • Encountering significant friction that prevents correct and consistent recycling.

Close to 50 potential solutions were generated to address the barriers preventing people from recycling consistently and correctly. These solutions were evaluated for potential impact and feasibility.  The top ranked intervention types include:

  • In-Home Information – addresses a lack of knowledge about what can be recycled
  • Feedback – addresses harmful actions and aspirational recycling
  • Fresh Start – moving to a new city increases openness to new patterns of behavior
  • Infrastructure Restrictions – uses friction to make it easier to develop positive habits and harder to continue negative ones
  • Personal Incentives – providing monetary or extrinsic motivation to recycle may encourage people to start and maintain a recycling habit
  • Social Norms – making behavior more public to increase extrinsic motivation
  • Tangible Incentives – creating incentives to increase extrinsic motivation
  • Infrastructure to Recycle – providing infrastructure to remove a behavioral barrier

Proposed Interventions

Experimental Design #1

The proposed intervention will study the fresh start effect and target residents who move into a new home to increase their participation in curbside recycling without increasing the contamination rate. The team proposed four hypotheses:

  • New residents who receive a Welcome Packet will be more likely to participate in curbside recycling than those who do not.
  • New residents who receive a Household Comparison letter with social norm information will be more likely to participate in curbside recycling than those who do not.
  • New residents who receive both a Welcome Packet and a Household Comparison letter will be more likely to continue recycling than those who only receive one or the other.
  • The impact on residents new to the city will not significantly differ from the impact on those moving to a new space within the city. 

The Welcome Packet will include a welcome letter from the mayor, a postcard about recycling (highlighting community norms), a visual describing what happens to recycled items, and a fridge magnet with recycling guidelines to serve as a reminder.

Solid Waste Management can use an RFID camera system to gather recycling data at a household level. To ensure that contamination does not increase as a result of the intervention, randomized cart audits can be conducted for a portion of the sample. All participants will be sent a survey at the experiment conclusion investigating self-reported behaviors, attitudes and values around recycling and sustainability, as well as connectedness to their community.

Expected Results: We expect a significant impact from these interventions, largely driven by forming proper recycling habits at a prime temporal landmark.  Recycling behavior is primarily driven by habit, so focusing on new habit formation allows effects to last for a long time.


Experimental Design #2

An “oops tag” informs residents that they placed non-recyclable items in their cart and reminds them which materials are and are not recyclable.  Behaviorally-informed oops-tagging combined with incentives should motivate residents to continue participating in curbside recycling, while decreasing contamination in their carts. The team proposed two hypotheses:

  • Behaviorally-informed oops tags will reduce contamination more than standard oops tags.
  • Adding disincentives (such as cart rejection or financial penalties) or incentives (such as financial rewards or products made of recyclable materials) to reinforce oops-tagging will further decrease contamination rates.

The current oops tag has a list of contaminants and collectors can mark the one found in a cart. The behaviorally-informed oops tag will highlight the social stigma by making the tag more visible and including an actionable recommendation to reduce the contamination found in the cart. 

Figure 1. Examples of current “oops tags.”

Expected Results: We expect the results of this pilot to be contingent on the incentives and disincentives tested. We expect the most extreme reactions to the cart rejection condition, but it remains to be seen if the intervention will successfully change behavior.

Why It Matters

Only 9% of the plastics generated are recycled, compared to 75% that are sent to landfill where they can take more than 400 years to degrade.4 Reducing the amount of material sent to landfills, which can cost more than $1 million per acre, can delay or prevent the need to construct additional ones.5,6 Additionally, the recycling industry creates 6-13 jobs per ton of material, compared to waste collection and landfill disposal, which creates less than one job per ton of material. 7

Estimates show that upwards of one-third of the material collected in curbside recycling programs is non-recyclable.8 Contaminants often prevent truckloads of materials from being recycled, as it is too costly for workers to remove them by hand. Decreasing contamination will make recycling more economically feasible for many communities.


  1. Environmental Protection Agency. (2018, October 26). Facts and Figures about Materials, Waste and Recycling. National Overview: Facts and Figures on Materials, Wastes and Recycling. Retrieved August 2019, from and-figures-materials#Trends1960-Today 
  2. Albeck-Ripka, L. (2018, May 29). Your Recycling Gets Recycled, Right? Maybe, or Maybe Not. Retrieved from 
  3. Bell, B. (2018, April 3). The Battle Against Recycling Contamination is Everyone's Battle. Retrieved from 
  4. Parker, L. (2018, December 20). Here's How Much Plastic Trash is Littering the Earth. Retrieved from 
  5. U.S. Environmental Protection Agency Office of Air and Radiation, Office of Air Quality Planning and Standards. (2014). Economic Impact Analysis for the Proposed New Subpart to the New Source Performance Standards.  Retrieved from
  6. Fitzwater, R. (2012, May). The Top Three Dividend Paying Waste Management. Retrieved from Seeking Alpha:
  7. Goldstein, J. (2014). From Waste to Jobs: What Achieving 75 Percent Recycling Means for California. Prepared for Natural Resources Defense Council (NRDC).