When you actually need new
About 8% of our shipments. The genuine cases for new:
DEF (diesel exhaust fluid) handling. ISO 22241 purity requirements are so tight that any prior-contents contamination — even from a previously food-grade bottle — poisons SCR catalysts in diesel engines. New-only inventory is the industry standard.
Pharmaceutical or aseptic-fill staging. Validated cleaning processes require known-history surfaces. Used bottles, even fully documented, often don't pass receiver audits in this space.
Some food applications with strict packaging-history requirements. Rare, but a handful of organic certifiers and a few European-market buyers will require virgin-only HDPE for direct-contact fluid storage.
UN/DOT-marked transport of regulated chemistries where the receiver's compliance team won't accept re-stamped markings on used bottles.
If you're not in one of those categories, used is the better choice on both cost and carbon.