This study was conducted to evaluate the effect of different water sources on survival rate and growth performance of Nile tilapia (O. niloticus) larvae during nursing period. Larvae (post yolk sac stage) were stocked at 50000 / pond and fed 48 % crude protein diet 6 times daily at rates of 35, 26 and 18% of their weight in the successive three weeks, respectively. Nine concrete ponds assigned for 3 treatments, triplicates in each. The ground water and agricultural drainage water were the water sources in the first and third treatments, respectively, while the second treatment received a 1: 1 mixture of the two water sources. Water samples, for some physico-chemical analysis, were monitored before pumping water into the ponds and within the ponds at each fry harvest. The experiment lasted for 21 days and replicated four times. At the end of each rearing period, fry number was estimated in each pond; the survival and growth rates were calculated. The results showed that the significantly highest survival and growth rates were obtained in the mixed water treatment. Mixing agricultural drainage water with ground water results the most suitable water quality for Nile tilapia performance than each of these sources separately. Generally, water quality parameters for the studied sources at the end of each rearing period were within the acceptable range for fish culture.