This good practice guide is focused on the DGT devices, which are the most widely used passive sampler for metals, covering the following aspects: ■ Principle ■ Handling passive sampling devices for metals ■ Estimation of appropriate field deployment time ■ A Good Practice Guide for the Use of DGTs ■ Passive sampling device preparation and assembly ■ Selection of sampling site and safety precautions ■ Passive sampling device deployment and retrieval ■ Extraction of analytes from passive sampling devices ■ Analysis ■ Calculations