Each year, the Joint Office of the HKSAR Government receives over 25,000 complaints on water seepage in multi-storey buildings and majority of the complaints are yet to be resolved. This is partly due to non-corporation of owners or occupiers of the alleged source sites thereby disallowing tests to be performed in the alleged source sites. Thus, this study attempts to investigate the causes of water seepage without entering the alleged source sites. It is based on the vibration signals obtained from the exposed waste pipes outside the alleged source sites and moisture data obtained from the alleged water seepage sites. To simulate the water seepage problem in multi-storey buildings, a washroom unit has been constructed in the laboratory. Drainage pipes in the washroom unit are connected to four common types of sanitary fitments including water closet, wash basin, bathtub and shower tray, which carry the domestic waste to the exposed waste pipes. The main challenge is to identify when the sanitary fitments are utilized based on the vibration signals obtained from the exposed waste pipes. Vibration induced by each sanitary fitment has distinct characteristics which can be identified through pattern recognition. Frequencies of pipe vibration are distinct features that can distinguish the sanitary fitments from each other. In addition, the relationship between frequencies and operating temperatures is also explored.