This International Standard develops procedures and prescribes the minimum accuracy required of water-level measurements made in wells using graduated steel tapes, electric tapes and air lines. Procedures and accuracy requirements for measuring water levels in a flowing well are also included, as are procedures required to establish a permanent measuring point. This International Standard discusses the advantages and limitations of each method and requirements for recording the data. This International Standard does not include methods that use automated electrical or mechanical means to measure and record water levels.