Detection and formation mechanisms of secondary nanoplastic released from drinking water bottles

•We describe an analytical method to detect release of nanoplastics in water matrix.•We measured released nanoparticles from water bottles under realistic use condition.•Quantitative studies of nanoplastics release are essential for hazards assessment.•We observe that mechanical stress alters structural characteristics of nanoplastics.•Understanding material degradation processes is crucial for analyzing nanoplastics.