Studies on plant invasives are largely focused on their impacts on plant community structure, native biodiversity, ecosystem services, and economy, but their ecosystem effects as high water-spenders are underestimated. Here, we report contrasting results in transpiration volumes in Prosopis juliflora (Sw.) DC (Prosopis juliflora), a widespread invasive alien, its native non-invasive congener, Prosopis cineraria (L.) Druce (P. cineraria), and an unrelated co-occurring native, Azadirachta indica A. Juss. (Azadirachta indica) at 3 sites spread across North and South between 200 and 550 m elevations in India. Our results demonstrate that P. juliflora shows higher transpiration than the native P. cineraria and A. indica at all the three investigated sites. The transpiration volumes of P. juliflora were 2.9–8 times higher than P. cineraria and A. indica at Jodhpur, and 6–11 times higher than A. indica at New Delhi and Hyderabad, respectively. The soil moisture content in the rhizosphere of P. juliflora dominated sites was 2–5 times lower than that of P. cineraria and A. indica dominated sites during summer. The results clearly demonstrate that invasive species transpire more water than the natives that consequently leads to decrease in soil moisture availability. Our investigations provide a strong rationale for managing the alien invasive P. juliflora and restoring native vegetation. Controlling the invasive species is particularly important for the regions with prolonged hot summers and freshwater shortages, such as tropical Asia, Middle East and tropical Africa, where P. juliflora has invaded vast areas.