The dairy sector in Bangladesh releases huge amounts of wastewater in the open environment. Dairy wastewater is enriched with different types of hazardous contaminants which can cause various health complications. The objective of this study was to evaluate the water quality of dairy wastewater by determining the physico-chemical properties of tap water and wastewater from three farms from Islamnagar zone, Savar, Dhaka, and also assess the significant impacts of wastewater on the environment. The most important physico-chemical properties investigated include: pH, total dissolved solids (TDS), electrical conductivity (EC), dissolved oxygen (DO), and microbial colony count. Results reveal that in tap water, the pH ranges from 7.11 to 7.20 and in wastewater, it was 7.30 to 7.77. The TDS in tap water ranged from 109 to 116 mg/L and in wastewater it ranged from 451 to 2000 mg/L. The EC values were found in tap water from 0.22 to 0.23 mS/cm, whereas in wastewater it ranged from 0.86 to 13.20 mS/cm. And for DO, the tap water showed a range from 4.21 to 6.25 mg/L and in wastewater it was found from 0.98 to 1.86 mg/L. The pH and TDS stayed within the standard limits in the physical-chemical parameters assessed, however, the EC and DO are not within the DoE (Department of Environment, Bangladesh) allowed limits. More microbial colonies have occurred in wastewater than that in tap water. The study demonstrates that the discharge of dairy wastewater in the open field is detrimental to our ecosystem, a proper treatment facility is essential.