Global ~50km (30 arcmin) surface water quality data from the dynamical surface water quality model (DynQual) from 1980-2019, with annual, monthly and daily temporal resolution. Simulations are made following the ISIMIP3a protocol (https://protocol.isimip.org/#/ISIMIP3a). Output data includes: Salinity; as indicated by TDS concentrations (mg l-1) Organic pollution; as indicated by BOD concentrations (mg l-1) Pathogen/bacterial pollution; as indicated by FC concentrations (cfu 100ml-1) Simulations were originally made at 5-arcmin resolution and aggregated to 30 arcmin 0.5 degree by summing the in-stream (routed) loadings and channel storage over the aggregated area (at daily, monthly and annual timesteps), and subsequently calculating in-stream concentrations. Please note the aggregation technique is provisional and thus the data is subject to change. Note. A minimum discharge threshold of 0.1 m3 s-1 was used when computing TDS, BOD and FC concentrations, as uncertainties in absolute values of water availabilities have large impacts on resulting in-stream concentrations. Concentrations in these gridcells are assigned as NA. Hydrology and water quality simulations made at DynQuals native spatial resolution (5 arcmin) can be found at: https://zenodo.org/records/14673871.