This study aimed to improve solar water disinfection through the use of photosensitizing substances (coumarin extracts of Citrus reticulata, Citrus aurantium and Citrus maxima). Solar disinfection shows negligible inhibition of fecal coliforms after 60 minutes of exposition to the sunlight. On the other hand, for photodynamic disinfection, complete inhibition is noted after 60 minutes of exposition. Regarding fecal enterococci, negligible inhibition is noted after 30 minutes for solar disinfection. On the other hand, for all coumarin extracts (Citrus reticulata, Citrus aurantium and Citrus maxima), complete inhibition is noted after 30 minutes of exposition to the sunlight. These results show that the use of coumarin extracts of Citrus reticulata, Citrus aurantium and Citrus maxima significantly improves solar disinfection. Additionally, these results show that fecal enterococci are more sensitive to photodynamic disinfection than fecal coliforms. This difference in sensitivity is due to the constitution of their cell walls. The wall of fecal coliforms (Gram-) is rich in lipopolysaccharides. These constitute a barrier to the passage of singlet oxygen. Whereas, the wall of fecal enterococci (Gram+) is easily penetrated by singlet oxygen (1O2) because it lacks lipopolysaccharides. After its passage, singlet oxygen destroys cellular constituents. This leads to the death of the bacterial cell.