This work studies catalytic reduction of nitrate with bimetallic catalysts supported on γ-alumina (Pd-Sn/Al₂O₃ and Pd-In/Al₂O₃). Pd-Sn/Al₂O₃ yielded higher NO₃⁻ conversion and selectivity towards N₂ than Pd-In/Al₂O₃ in synthetic water (deionized water with 100 mg/L NO₃⁻). The Pd-Sn/Al₂O₃ catalyst showed highly stable behaviour, without signs of deactivation upon ten consecutive runs of 6 h each, where almost equal low selectivity to NH₄⁺ (absence of NO₂⁻) was maintained at high nearly constant nitrate conversion (≈ 90%). The presence of anions (Cl⁻, SO₄²⁻ and HCO₃⁻) in the reaction medium decreased NO₃⁻ conversion and the selectivity towards N₂. Chloride showed a moderately negative effect at relatively low concentration. The effect of SO₄²⁻ and HCO₃⁻ was more pronounced, being the second the most detrimental to the catalytic activity. The selectivity towards N₂ was also negatively affected by the presence of those anions following the sequence HCO₃⁻ > SO₄²⁻ > Cl⁻. However, the joint presence of Cl⁻ or SO₄²⁻ with HCO₃⁻ reduced the negative effect of the latter. The Pd-Sn/Al₂O₃ catalyst also showed high activity in NO₃⁻ reduction from drinking waters of weak mineralization, with a slightly increase of the selectivity towards NH₄⁺ with respect to the obtained in deionized water with NO₃⁻ as the only anion.