It is established that the environmental impact caused by purified wastewater at wastewater treatment plants (WWTP) is determined by several factors: the performance of purification plants, the volume and degree of wastewater pollution, the specificity of the pollutants removed and the purification capacity WWTP. The highest degree of wastewater treatment is achieved at the leachate treatment station generated at the landfill in the commune of Bubueci at the Corporation ―Regia Autosalubritate‖, 205 2, Uzinelor Street, Chisinau. This is explained by the fact, that reverse osmosis is used in the installation. This fact ensures a high degree of purification for pollutants (chlorine ions and sulfates), which by the biological method of purification, their removal is only about 10% of their amount. A high level of environmental pollution is caused by wastewater from M.I. „Vinăria Bardar‖ Corporation, and treated at the local purification station, which do not meet the requirements of GD 950/2013, Annex 1. Exceedances for CODCr, are 1.61 times, for the first case and 1.04 times for the second case. For BOD5 the overruns are 2.54 times, and 1.82 times, respectively for the first and second case. This is explained by the degree of inadequate treatment of wastewater. The characteristic of the water from the ―Negară Vasile‖ pond, according to the requirements of GD no. 890, water refers to the quality of class 2, by the content of nitrate and chloride nitrogen – to quality class 1, by the sulfate content – to class V, total iron – to class IV and by the content of zinc refers to the quality of class III. An essential impact on the Chisinau treatment plant is caused by JSC ―JLC‖ Lactate, Chisinau. According to HG-950/2013, Annex 1, practically, after all the pollutants from the wastewater discharged into the sewerage, the admissible limit values are exceeded. Exceedances are: CODCr: 6.9 times; 3.7; 4.1; 33.9 and 5.7 times. For BOD5: 7.7 times; 4.4; 4.8; 36.4 and 6.1 times, and for chlorides, these are: 1.7 times; 1.3 and 1.1 times. In total phosphorus, the exceedances represent: 2.1 times; 1.2; 1.4; 4.4 and 3.0 times; and for fats, they are: 4.7 times; 11.0; 17.7; 9.5; 12.6; 3.2 and 1.5 times.