Patent ID: 7021137

Claim:
Apparatus for measuring aqueous liquid layers in a well comprising: (a) an elongated water level measuring means positioned along the length of said well having a first string of series connected resistors together with a series of water sensing means, each water sensing means being electrically coupled to an associated resistor of said string of series connected resistors for electrically removing a resistor from said string of resistors upon the presence of water at each water sensing means; (b) water level measuring means enabling measurement of the resistance of said string of resistors when said elongated water level measuring means is positioned within said well; and wherein each water sensing means comprises a pair of electrical contacts for directly contacting said aqueous liquid along with a voltage controlled switch coupled between said pair of electrical contacts and a resistor of said series of resistors; and wherein said elongated water level measuring means is mechanically coupled to support means extending along the length of said well for retaining said water level elongated measuring means in place within said well between well inspections, thereby eliminating lowering and raising said elongated water level measuring means into and out of said well that may require subsequent decontamination procedures; and wherein the elongated water level measuring means includes a second string of series connected resistors having a total resistance proportional to the total length of the elongated water level measuring means extending to the bottom of said well and further including; means for subtracting the measured resistance of said first series resistance circuit from the measured resistance of said second series circuit for indicating the thickness of a water layer in said well.