An apparatus detects a leak of an electrically conductive fluid from a
disposable plastic bag used in mixing applications, such as during
bioprocessing in a sterile environment. In one embodiment, the bag is
associated with a sensor for detecting a leak from an interior
compartment. The sensor may be arranged to detect either a leak internal
to the at least two material layers of the bag or external to the outer
layer, or both. Related methods are also disclosed.