Drilling fluid plays a crucial role in drilling operations, significantly impacting performance by managing bottom hole pressure, ensuring wellbore stability, and maintaining hole cleanliness. Without effective drilling fluid, issues such as poor well control, unstable wellbores, inadequate transmission capacity, excessive torque, pipe sticking, drag, and damage would occur. This study investigates the enhancement of water-based bentonite drilling mud properties by adding calcium carbonate (CaCO3) and xanthan gum polymer. Various concentrations of calcium carbonate (2, 4, and 6 percentage by weight (%wt)) and xanthan gum (0.1, 0.2, 0.3, and 0.4 wt%) were tested to evaluate their effects on rheology and filtration properties. The plastic viscosity of fluids with calcium carbonate varied slightly from 6 to 7.5 cp, while density increased significantly, peaking at 8.93 ppg at 6 wt%. The filtration rate showed minimal change, decreasing slightly from 16.8 ml to 16.4 ml, and cake thickness remained constant. Xanthan gum significantly increased gel strength from 0.1 wt% to 0.3 wt% (52 to 72 lb/100ft2 at 10 min), with negligible changes beyond 0.3 wt%. Filtration volume decreased notably from 12.2 ml at 0.1 wt% to 10.2 ml at 0.4 wt%, and cake thickness reduced from 2 mm to 1.5 mm, highlighting xanthan gum's effectiveness in controlling fluid loss.