Overland flow data and soil water tension data at 10cm, 30cm, & 50cm from four manipulation plot sites located across the Pontbren study site in mid-Wales, UK. The manipulation plots were established at different locations across the site between 2005-2012 as part of the Pontbren Catchment Study Land Use and Management Multi-Scale Experimental Programme. Manipulation plot sites were located on improved grassland hillslopes and each site had three replicate plots. Following baseline monitoring different land use treatments were applied to individual plots. The different treatments were grazing (i.e. the control or no change), ungrazed and ungrazed with planting of trees. Details of the treatments can be found in the Pontbren Catchment Study Data Catalogue. Overland flow from a 10m x 2.5m isolated plot was measured within each treatment plot at each of the manipulation plot sites. Overland flow data were measured using tipping bucket monitoring systems and the number of tips occurring in a given time period recorded. Soil water tension (cm H2O) data were measured in each treatment plot using an array of tensiometers installed at 10 cm, 30 cm, and 50 cm depth. The dataset contains four folders relating to the four manipulation plot sites. Within each folder are subfolders for overland flow runoff and soil water tension. Data are provided as text files and generally split into six-month blocks. Neutron probe access tubes were also installed in each of the manipulation plots to measure volumetric moisture content (cm3 cm-3) and two of the manipulation plots sites (1 and 4) also had rain gauges installed monitoring precipitation. The data thus collected are also available from the Environmental Information Data Centre.