The objective of this work was to assess the effectiveness of using near UV light to disinfect water supplies for potential applications in developing countries. A pilot scale photoreactor comprised of non-tracking compound parabolic collectors installed at Plataforma Solar de Almeria was examined and a comparison of disinfection efficiency using E coli K-12 was carried out with a reactor configuration of 3 and 1 m(2) illuminated area. Tests were also carried out using suspensions of titanium dioxide (TiO2) at concentrations ranging from 0 to 9 mg/l. The removal of E. coli K-12 from initial concentrations of 1 x 10(5) CFU/ml to below the limit of detection was achieved both with and without the use of TiO2. Levels of inactivation in 35 l of inoculated water of up to 4-log removal were achieved in under 30 min. The addition of TiO2 created an enhancement to the process only at the 3 mg/l dose. However, the results have also suggested the possibility that another, disinfection mechanism, possibly governed by the frequency of intermittent UV light exposure, was regulating the overall inactivation kinetics of the trials. (C) 2004 Elsevier Ltd. All rights reserved.