The aim of the present research work was to evaluate the effects on water consumption, yield, and fruit quality of two tomato cultivars ('Diana' and 'Naomi') of two levels of electrical conductivity (EC) of the nutrient solution, i.e. night high and day low vs low EC all day. The use of a nutrient solution with high EC during the night (6 dS/m) did not modify yield (4.5 and 3.0 kg/plant, respectively, for 'Diana' and 'Naomi'), number, and mass of fruits. The values for 'Diana' and 'Naomi' of fruit dry mass (5.2 and 7.6 g/100 g of fresh weight, respectively), titratable acidity (0.57 g/100 ml of juice of citric acid, on average), and vitamin C (20.6 and 32.5 mg/100 ml of juice of ascorbic acid, respectively) were not influenced by EC. On the contrary, the total soluble solids were higher with low/high (day/night) EC than low/low EC (5.8 vs 5.3 ̊Brix, on average for cultivars). The daily water consumption was not modified by the nutrient solution EC.