The effect of treated and untreated wastewater on Pseudomonas spp. bacteria was detected. Soil samples were collected from a cotton cultivated field that divided into five plots which irrigated with different irrigation water : regular irrigation water (W0), well water (W1), untreated wastewater (W2), and two ways treated wastewater (W3,W4). The numbers of Pseudomonas spp. bacteria were significantly high in soil irrigated with wastewater in general (W3, W2, W4 respectively). The differences between these treatments (W3, W2, W4) were highly significant compared to the soil irrigated with well water (W1) and the soil irrigate with regular irrigation water (W0), as the last two treatments (W0,W1) did not differ significantly from each other. The study showed the presence of Pseudomonas fluorescens bacteria in the soil irrigated with regular water and well water (W0, W1) and the absence of these bacteria in soil irrigated with waste water. The study also indicates the present of Pseudomonas aeruginosa bacteria in the soil irrigated with treated and untreated wastewater (W2,W3,W4) and in large numbers, in addition to their presence (in low numbers) in soil irrigated with regular water and well water (W0,W1). This clarifies the role of using wastewater in changing soil environment and its natural flora.