Solar pasteurisation is a simple, robust, and sustainable method for the disinfection of raw water, which can be particularly relevant in remote areas. The process consisted of an open water loop with a flat plate solar collector, a thermostatic valve, a tank and a heat exchanger in series. It was feed with river water supplied by gravity from a tank at 3 meters high. It was tested in outdoor conditions with real river water and operated with a fully passive control of the pasteurisation temperature. On sunny days in September, 850 litres of water pasteurised at over 60°C and 68°C were produced per day in a reproducible way, i.e. almost 370 L.m -2 .day -1 . The specific solar energy required was of the order of 15 kWhsol.m -3 .

Experimental daily amount of pasteurised water of almost one cubic meter have been achieved by increasing the hydraulic pressure at the inlet of the open water loop. The total absence of the two main bacterial indicators naturally present in the surface water collected, i.e. E. coli and Enterococcus, was verified at the outlet of the process. The development of a numerical model, validated by experimental results obtained, has made it possible to assess the potential field of application of this solar pasteurisation system.