Drain and duct location Water Works has an established process for tracing burst or blocked rising mains and other narrow diameter pipes and ducts. The flexi trace system energizes the entire length of the tuned coil, giving a strong reliable signal along the length of the pipe.  Available for narrow diameter pipes and ducts of 5mm - 10mm.  Max length 80 metres. For longer pipes and ducts, Water Works has a range of super slim sondes that can be attached to a 300m length coil and traced using radio-detection.