Field disinfection of water in a large solar photoreactor (35-701) was conducted at "natural" temperature of 35 degrees C by different photocatalytic processes: sunlight/TiO2, sunlight/TiO2/Fe3+, sunlight/Fe3+/H2O2 and referenced by the control experiment of direct sunlight alone. Experiments under direct solar radiation were carried out using a compound parabolic collector (CPC) placed at the EPFL in Lausanne, Switzerland. Leman Lake water contaminated with E. coli K 12 was exposed to sunlight in sunny days on 2003. In these conditions, under solar irradiation, total disinfection was not reached after 5 h of treatment; and bacterial recovery was observed during the subsequent 24 h in the dark. The addition of TiO2, TiO2/Fe3+ or Fe3+/H2O2 to the water accelerates the bactericidal action of sunlight, leading to total disinfection by helio-photocatalysis. (c) 2007 Elsevier B.V. All rights reserved.