What a Mexican PET Deposit-Refund Pilot Must Measure: Consumer Response, Collector Access and Collector Income

Background: Mexico reports collecting 64% of its PET bottles against targets of 70% (2025) and 80% (2030), and informal collectors carry much of that work. A deposit-refund system (DRS) could raise recovery but could also take material and income from them; Mexico’s 2026 Circular Economy Law recognizes base recyclers but creates no DRS. Methods: We build a stock-and-flow model of containers, consumer returns and collector entry and exit, anchor inputs to Mexican sources where they exist, and add a calculation of collector income from six quarters of the national ENOE employment survey. Results: Across simulated systems, a 1.5 MXN deposit with collectors receiving 30% of it on the containers they hand in reaches 80% recovery while keeping at least 90% of collectors in 68–95% of systems, the upper end assuming an optimistic reading of collector income; a 3.0 MXN deposit reaches 92–99%. Failures are almost always consumer-response failures; displacement appears when collector access is low. Consumer hassle cost, collector income margin, entry sensitivity and the accessible share of discards drive most of the uncertainty. Conclusions: A pilot should measure consumer returns at three or more deposit levels, collector access and income, and audited recovery, with decision thresholds we derive.