The evaluation of individual effects of surfactants or other ingredients does not reflect the influence of a detergent on the aquatic environment, being important to estimate the effects of detergent as a whole. In the present study is evaluating the influence of 3 types of detergents on the NH4+ nitrification process in water: 2 solid detergents (DS-1 and DS-2) and one liquid detergent (DL). The nitrification process was evaluated in the water from the river Nistru, near Palanca village, in which were added of 2,2-2,5 mg/dm3 NH4+, 1-10-100 mg/dm3 of DS-1 and DS-2 and 0,1-0,5-1,0 ml/dm3 of DL. The NH4+ →NO2- step in water without detergent lasted 8 days. At the addition of 1-10 mg/dm3 of DS-1 and DS-2 the process took 9-10 days and at 100 mg/dm3 was in 19-24 days. It was shown that at the addition of 0,1 ml/dm3 DL the step lasted 19 days, and in the presence of 0,5-1,0 ml/dm3 after 30 days there were still 56-88% of ammonium ions left. The NO2- → NO3- step in water without detergent lasted 13 days. When adding 1-10 mg/dm3 of DS-1 and DS-2 the process lasted 13-17 days and in the presence of 100 mg/dm3 the stage duration was 26 days for DS-1 and more than 30 days for DS-2, finally nitrates formed after nitrification being 14,6-19,8 mg/dm3, and in water without the addition of detergents – 22,4 mg/dm3. DL has a specific influence in the second stage of nitrification. At the addition of 0,1 ml/dm3 DL the step lasted 20 days, and in the presence of 0,5-1,0 ml/dm3 after 30 days in solutions were only 0,6-2,5 mg/dm3 NO2-, in final being only 1,01-1,68 mg/dm3 of nitrates. Thus, it is necessary to evaluate the influence of detergents (not only surfactants) on water quality, including in the wastewater treatment process.