Computational fluid dynamic simulation of small leaks in a pipe having 0.1m diameter has been performed under realistic velocities and pressures using a 3D turbulent flow model of well tested CFD code. The steady state simulations have shown clear signature in the pressure and pressure gradient variations along the pipe. For very small leaks (below 1l/min), this signature in not very strong in the pressure variation, but very clear in the pressure gradient. The averaged power spectral density (PSD) as well as FFT of the pressure fluctuations based on transient Detached Eddy Simulations (DESs) are presented for different locations around the leak position. These results show that the presence of a leak causes measurable differences in the magnitude and frequency of the pressure signal spectrum and also in the averaged PSD for the range of 220–500Hz frequency.