In this work, an expedite flow method for the combined determination of major nutrients, nitrogen base ions (nitrate, nitrite and ammonium) and phosphate, is described for seasonal monitoring of inland bathing waters. Individual determinations were adapted and comprised within the same manifold to attain a comprehensive assessment of the environmental status of natural waters. The multiparametric determination was performed to explore the features of a sequential injection analysis technique yielding a real-time assessment of various parameters and effective in-line sample handling. The sequential injection multiparametric method enabled the determination within the ranges: 15.0-150 μM nitrate; 0.15-5.00 μM nitrite; 1.00-60 μM ammonium; and 0.2-30 μM phosphate. The determination rates provided a full nutrient analysis within 7 minutes, an overwhelming improvement in relation to the individual determination of each parameter. The described method was successfully applied to seasonal monitoring of six inland bathing waters dealing in-line with sample variability.