Abstract: A liquid tank leakage detection system includes a standpipe and associated measuring pipe together with a sealing connection to the filler pipe of a liquid tank system. A liquid level detector used in cooperation with the measuring pipe includes a float coupled to a measuring beam having one end fixed and the other end coupled to the float. Level changes within the liquid system produce position changes of the float which in turn causes bending or flexing of the beam. A bridge detecting circuit including strain gauges coupled to the flexing beam is operative to provide an output signal indicative of the extent of liquid level changes. A thermocouple is positioned within the liquid tank to provide a temperature compensating signal for use by the measurement system.