The use of pesticides has grown dramatically to increase crop yields, but there are risks to the environment and public health. Water contamination is becoming a bigger problem due to careless implementation and lax laws. Pesticides, however, can boost agricultural output and shield crops from pests. Few studies look at surface water year-round because of the small amount and short duration of pesticide residues in crops and soils. Most studies concentrate on the risks related to pesticides. Pesticides can bioaccumulate more readily in aquatic species than in terrestrial ones. However, data to forecast how particular pesticide concentrations in agricultural runoff will impact water quality downstream are lacking. The physical, chemical, biological, and hydrological processes influencing pesticide behavior in aquatic and agricultural settings and during transitions between them require basic research. Additionally, data regarding the dynamics of population recovery in connection to pesticide concentration and species stress, as well as the possible toxicity of pesticides, are required. This chapter will discuss how changes in precipitation patterns brought about by climate change affect the availability and quality of water. Analyze how pesticide drift, leaching, and runoff affect human health and aquatic ecosystems, particularly in light of shifting hydrological cycles.