Monitoring the concentration of nitrate (NO3⁻) and nitrite (NO2⁻) ions in water is essential due to their considerable impact on both environmental and human health. In this work, screen-printing technology was employed to fabricate electrochemical sensors with high reproducibility and reliable analytical performance. For nitrate detection, copper (Cu) was chosen as the electroactive material owing to its high electrical conductivity (5.8×10⁷S/m), which enhances charge transfer kinetics. Well-defined copper microcrystals were electrodeposited onto carbon screen-printed electrodes (SPCEs) via cyclic voltammetry, resulting in excellent catalytic activity toward NO3⁻electroreduction. The developed sensor demonstrated a sensitivity of 44.71 µA/mM, a detection limit (LoD) of 0.87 µM, and a linear dynamic range between 50 µM and 3 mM. It also showed good reproducibility (maximum relative standard deviation, RSD, of 4%) and repeatability (RSD of 5.5% after ten consecutive measurements). For nitrite detection, a mixture of copper and manganese oxides (CuO and MnO2) was electrodeposited onto a SPCE. These oxides act synergistically as electrocatalysts for the oxidation of N 02- to NO3⁻, leveraging their complementary redox properties. The resulting sensor exhibited high catalytic efficiency, with a sensitivity of 10.83 µA/µM, an LoD of 0.071 µM, and a linear response across the 0.2-60 µM range. Reproducibility (maximum RSD of 2.91%) and repeatability (up to three uses with a maximum RSD of 6.5%) tests were performed. Furthermore, simultaneous monitoring of NO3⁻and NO2⁻ions is viable by employing portable multichannel potentiostats, which allow independent multiple measurements. This approach enables efficient, real-time, and on-site multiplexed water quality analysis.