The problem of leak location is actually a time delay estimation (TDE) problem. Since most exist-ing TDE methods may encounter the problem of high computational complexity when used for online leak location. This paper presents a fast leak locating method based on wavelet transform (WT). The method first gets a rough estimate of the time delay from the WT coefficients of the pressure signals at the largest scale, then keeps refining the estimate using WT coefficients on smaller and smaller scales. Quantitative analyses and test results based on real data show that the method reduces the computational complexity while main-taining the time delay estimation accuracy.