Abstract: The mechanical signaling device is used for indicating when contaminates are present in water in a manhole so that the contaminated can be cleaned out of the manhole before the contaminates are released into the environment. The mechanical signaling device has a flag which moves up to a visible warning position when triggered by contaminates entering a float in the manhole which will then weigh the float down which pulls on a cable attached to a trigger which releases a spring loaded flag to pop up into view. The flag is easily reset by pushing it back down against the force of the spring until it is reset for release by the triggering mechanism. The mechanical signaling mechanism is housed in a pipe and has a protective cover preventing snow from resting on the top cover, further a top cover seals pipe when the flag is down.