Tomato is one of the most demanding crops in terms of water and fertilizer inputs. To meet irrigation water demand, growers use surface and ground water resources. These resources are in decline. Realizing the importance of water, tomato yield under deficit irrigation regimes, and different Nitrogen (N) levels, was studied during 2015 and 2016 at the research farm of the University of Agriculture Peshawar, Pakistan, using factorial arrangement of randomized complete block design (RCBD). These factors were four irrigation levels; full irrigation (I0), 15% deficit (I15), 30% deficit (I30) and 45% deficit (I45); and four nitrogen doses;100% of recommended dose (120 kg ha-1) (N100), 85% of recommended dose (N85), 70% of recommended dose (N70) and 55% of recommended dose (N55). Frequency Domain Reflectometry (FDR) was used for soil moisture monitoring. Io was based on 30% of management allowed deficit. Current study results indicated that deficit irrigation (I15, I30 and I45) had significant effect (P<0.05) on plant height, number of fruits per plant, leaf area index (LAI), total yield, marketable yield, water productivity, nitrogen uptake, Potash uptake (K) and Nitrogen use efficiency (NUE). Compared to I45, full irrigation enhanced, number of fruits per plant, LAI, total yield, marketable yield, N uptake, K uptake and NUE by 34, 30, 24, 25, 13, 15.5 and 24%, respectively. Water productivity was 25.8% higher for I45 compared to I0. Effect of deficit irrigation on dry-to-fresh weight ratio, days to 50% flowering, individual fruit weight and Phosphorous (P) uptake was found to be non-significant. Effect of Nitrogen doses number of fruits per plant, LAI, total yield and NUE was found to be highly significant. However, the effect on dry-to-fresh weight ratio, plant height, days to 50% flowering, individual fruit weight, marketable yield, water productivity and NPK uptake were found to be non-significant. Maximum dry-to-fresh weight ratio (0.83) was recorded for N70, maximum plant height (77.7 cm) was obtained under N85, maximum number of days to 50% flowering (42.3) were recorded for N100, highest individual fruit weight (66.6 g) was obtained in N85, while P uptake (10.2 kg ha- 1) was obtained in N85 and maximum NUE (414) was recorded for N55. Recommended dose of Nitrogen (N100) enhanced number of fruits per plant (12.6%), LAI (22.8%), total yield (8%), marketable yield (6.9%), water productivity (6.3%), N (5.3%) and K uptake (9.8%) compared to N55. Deficit irrigation increased the risk of fruit damage in tomato plants. Water productivity decreased with increasing irrigation levels. Nitrogen and potash uptake were increased with increasing irrigation levels, while phosphorous uptake was not significantly affected. Increasing irrigation and Nitrogen doses increased the risk of nitrate leaching beyond the root zone, making it unavailable for plant uptake. Full irrigation and Nitrogen (120 kg ha-1) is recommended for higher total yields, however, 45% less nitrogen can be applied through a drip irrigation system without compromising marketable yield. In areas where water is a scarce commodity, highest water productivity can be achieved with 45% deficit irrigation. Simulation of Nitrate leaching with HYDRUS-1D showed that with decreased irrigation levels below field capacity, and with the recommended dose of Nitrogen, nitrate leaching was higher than with reduced Nitrogen doses and full irrigation. Increasing irrigation levels above field capacity with recommended dose of Nitrogen showed higher nitrate leaching than increasing Nitrogen doses above recommended dose of Nitrogen and full irrigation. HYDRUS-1D can be efficiently used for nitrate leaching simulation.