A new method was developed to test nitrate levels in drinking water. It involves using UV light to turn nitrate into nitrite, which can then be measured. The method is accurate, with a detection limit of 0.053 μmol/L and a range of 0.2-40 μmol/L. Testing a 20 μmol/L sample multiple times showed consistent results with a small variation of 2.22%. The method was also tested on real drinking water samples, showing recoveries between 90.9%-100.6%.