General Background: Groundwater is a critical resource for many regions, particularly in arid and semi-arid areas, where surface water is scarce. Specific Background: In Diyala Governorate, Iraq, reliance on groundwater is high, especially in the northeastern and western regions, which use it extensively for domestic and agricultural purposes. Knowledge Gap: Despite its importance, there is limited comprehensive analysis comparing the quality and suitability of groundwater across different areas within the governorate. Aims: This study aims to analyze the chemical and physical properties of groundwater from selected wells in the northeastern (Khanaqin and Saadia) and western (Khalis and Dali Abbas) regions of Diyala Governorate to determine its suitability for use. Results: The analysis revealed a significant increase in nitrate concentrations, particularly in the western regions, with a value of 26.3 mg/L, and higher nitrite levels were also observed. The pH levels indicated a tendency toward acidity in the northeastern regions (7.1-7.2), whereas the western regions showed values closer to the acidity standard (7.05-7.45). The dissolved salts were notably lower in Khalis (575 mg/L). Novelty: The study uniquely highlights the variation in groundwater quality across different regions of the governorate, revealing critical discrepancies in water composition and well depth that have not been previously documented. Implications: These findings underscore the need for region-specific water management strategies in Diyala Governorate, particularly in the eastern regions where groundwater characteristics align more closely with international standards, making them more suitable for sustainable groundwater investment and utilization. Highlights: Significant regional differences in groundwater quality were observed. Higher nitrate/nitrite concentrations found in western regions. Eastern regions' groundwater closer to international standards. Keywords: Groundwater quality, Diyala Governorate, nitrate concentration, pH levels, water suitability