Groundwater geochemistry studies the chemical composition and quality of groundwater, focusing on contamination from human activities like industrial discharge and agricultural runoff. With freshwater scarcity being a global concern, its essential to understand the geochemical processes that lead to pollution, including the interactions between contaminants and geological materials. Analysis of water samples reveals the presence of heavy metals and nitrates, and geochemical modelling helps assess pollutant transport and degradation pathways. Poor waste management and excessive agricultural inputs have degraded shallow aquifers, necessitating effective management strategies to mitigate contamination. The book emphasizes the importance of isotopic analysis, mineral interactions, and climate impacts on groundwater dynamics, highlighting the complex interplay within the hydrological cycle and its implications for environmental management. Pesticides in soil interact with microbial activity and soil properties, affecting their persistence and potential groundwater contamination, necessitating careful management and optimized application strategies. Advancements in remediation techniques, such as pulsed pumping and in situ bioremediation, enhance the efficiency of contaminant extraction and treatment, particularly for challenging organic pollutants in various subsurface environments. Nitrate contamination in shallow aquifers arises from industrial, agricultural, and municipal sources, necessitating integrated modeling of unsaturated and saturated zones to manage its transport. High arsenic levels in Western Anatolia highlight the need for advanced treatment methods and coordinated water resource management. Groundwater remediation strategies involve complex decisions between in situ treatments and extraction methods, requiring collaboration between hydrogeologists and engineers.