Water quality assessment is a fundamental aspect of environmental monitoring, directly influencing public health, agricultural sustainability, and industrial processes. This chapter presents a comprehensive review of chemical analytical techniques for surface and groundwater quality evaluation, categorized into classical wet chemical methods and instrumental approaches. Classical techniques, including gravimetric, titrimetric, and colorimetric methods, provide cost-effective and robust analytical frameworks. In contrast, instrumental techniques, such as electrochemical (potentiometry, voltammetry, coulometry), spectroscopic (UV-Vis spectroscopy, atomic absorption spectroscopy, Fourier-transform infrared spectroscopy), chromatographic (gas and ion chromatography), and mass spectrometric (ICP-MS) methods, offer enhanced precision, sensitivity, and specificity for detecting trace contaminants. This critical evaluation underscores the strengths and limitations of these methodologies, particularly regarding detection limits, selectivity, and matrix effects.