9Process Intensification (PI) refers to the use of novel process technologies to achieve 10 significant (order of magnitude) size reduction in individual unit operations, or the complete 11 removal of process steps by performing multiple functions in fewer steps. This should lead to 12 significant reductions in capital and running costs, and improvements in process efficiency 13 and safety. There are numerous examples of PI being successfully implemented in the oil and 14 gas, pharmaceutical, food and drink, and fine chemical industries, but few in the water 15 industry. There are however a range of drivers for process intensification within the water 16 industry. These include ever more stringent environmental standards and more intractable 17 pollutants. The aim of this review was to identify PI technologies that could be used in the 18 future UK water industry, but require further technical development (to increase their TRL), 19 or transfer from other industries. Recommendations for technologies are given, as well as 20 routes to their implementation. 21 22 Highlights: 23 PI can significantly reduce the size of unit operations, remove process steps and make 24 processes more efficient and safer 25  The UK water industry is facing environmental, financial, and land constraints, all of 26 which may be drivers toward more efficient and innovative processing 27  There is significant potential for the application of novel PI technologies 28 2