ISO International Standard

ISO 21413:2005 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. ISO 21413:2005 discusses the advantages and limitations of each method and requirements for recording the data. ISO 21413:2005 does not include methods that use automated electrical or mechanical means to measure and record water levels.