Oil palm plantations have faced heightened scrutiny over their water consumption and environmental consequences; yet, quantitative evaluations of their water footprint (WF) in relation to watershed-level water availability are still limited. This study assesses the green, blue and grey WFs of oil palm plantation in the Kampar Watershed, Riau, Indonesia, while integrating regional water balance analysis with the FJ Mock technique and evapotranspiration (ET) modelling utilising the Penman-Monteith equation. The total WF in Kampar Regency was 327.37 m³/t (green: 170.49 m³/t; grey: 129.10 m³/t; blue: 27.78 m³/t), whereas Pelalawan Regency recorded 272.88 m³/t (green: 159.82 m³/t; grey: 84.67 m³/t; blue: 28.39 m³/t). Although the Kampar River has adequate water resources, the growth of plantations raises sustainability issues. Grey water footprint scores (WFS) denote moderate environmental performance in both regions. Sensitivity study indicates that fluctuations in rainfall and yield can markedly affect WF estimates, particularly the grey component. This comprehensive strategy emphasises the necessity for improved fertiliser and water management techniques to guarantee sustainable oil palm cultivation in water-abundant yet environmentally delicate tropical catchments.