An elongated capacitance probe for use in a measuring system for locating a liquid level interface in a tank is provided. The probe includes an outer casing having first and second substantially semi-circular matingly engaging portions, the outer casing having top and bottom ends defining a length thereof approximately equal to a height of the tank. Spacers are mounted in opposed relation in the outer casing to form spacer pairs, the spacer pairs located in a spaced apart relationship along a longitudinal axis of the outer casing. A plurality of ground plates are mounted in a spaced apart relationship in the spacer pairs. To locate the liquid level interface in the tank, one or more capacitor plates are mounted in the spacer pairs, each capacitor plate mounted between a pair of ground plates, and extending substantially the length of the outer casing. Each of the capacitor plates in combination with a ground plate forms a capacitor extending substantially the entire length of the outer casing. An additional capacitor plate is mounted in the spacer pairs adjacent the bottom end of the outer casing for measuring an amount of water in the tank.