A procedure for determining the sulfate content in drinking water and natural water systems has been developed. Interferences were removed with an ion‐exchange column and an acid treatment before precipitating the sulfate as the 2‐perimidinylammonium sulfate. This compound was then thermally decomposed to form sulfur dioxide which was measured by the West‐Gaeke procedure. The method has a working range of 0–120 ppm with a relative standard deviation of +2.0$ and a sensitivity of 1.8 ppm. Total untreated sample requirement is less than 20 ml, out of which replicate determinations can be performed.