The datafile is part of a study to determine elemental -with a focus on heavy metal- contents in organisms of drinking water reservoirs (Brabantse Biesbosch, the Netherlands). Heavy metals are naturally omnipresent in aquatic systems. Excess amounts of heavy metals can accumulate in organisms of pollution impacted systems and biomagnify or biodilute across a food web. Analysing the food web structure and metal contents of the organisms can help unravel the pathways of biomagnification or biodilution and gain insight in trophic linkages. The measured heavy metals and other elements in organisms of the Biesbosch reservoirs were linked to stable isotopic signatures (as measured in a previous study by Verstijnen et al. (2019)).