A study was conducted to evaluate the persistent behaviour of pretilachlor in groundwater by applying uniformconcentrations: T0 – Untreated Control, T1 – Pretilachlor 37% EW (Emulsifiable in Water) at 0.5 µg/mL, andT2–Pretilachlor 37% EW (Emulsifiable in Water) at 1.0 µg/mL. The spiked samples were exposed to sunlight. Water samples were collected at various intervals (0.2, 1, 2, 5, 10, 20, 30, 40, and 50 days). All samples were analyseduntil the residues dropped below the detectable level. The quantification of Pretilachlor residues was conductedusing a validated gas chromatography with a flame ionisation detector (GC-FID), with key parameters includingaDB-1MS column (30 m × 0.25 mm ID, 0.25 µm film thickness), an injector temperature of 250° C, a detector temperature of 260° C, and a column oven temperature of 240° C. The analysis involved a 1.0 µL injection volumewith a split ratio of 10 and utilised nitrogen as the carrier gas at a flow rate of 2.0 mL/min. The total run time was6.0 minutes, with a retention time for Pretilachlor of approximately 3.2 minutes. The method's limit of detectionwas0.01 µg/mL, and the limit of quantification (LOQ) was 0.03 µg/mL based on recovery. The residues of Pretilachlor in the aqueous solution decreased to below the detectable level by the 50th day. The DT50 (Half-Life) of Pretilachlor was determined through regression analysis of the dissipation data, resulting in a DT50 value of 14.37days for the T1 dose and 14.42 days for the T2 dose.