Rainwater harvesting (RWH) is a practice of growing importance in the United Kingdom, particularly in the southeast of England where the water availability per person is even less than in many Mediterranean countries. Although there is a huge amount of rainfall in the north and west of England and Wales, water resources in the southeast and east of England are under pressure due to the growing population and the changing climate. Therefore, RWH becomes particularly important to reduce the dependence on the mains water supply. In the present study, suitable areas for RWH in the UK have been identified using a geographic information system-based decision support system (DSS) and remote sensing. The DSS undertakes a combination of thematic layers such as rainfall surplus, slope, curve number, land cover/use, and soil texture. The spatial extents of suitability areas for RWH were identified using multi-criteria evaluation. The spatial distribution of the suitability map shows that the excellent suitable areas for RWH are in the northwest of UK but less suitable areas in the northern and eastern parts. On average, the suitability for RWH in the UK was found that 18.95 and 27.25 % of the area are excellent and good, about 23.53 % is moderate, whilst 30.26 and 0.02 % are unsuitable and poor, respectively. The use of a number of RWH sites in the excellent areas is recommended to ensure successful implementation of RWH systems.