Atomic absorption analysis, recommended by CTI drift code (ATC-140) is one of the most accurate chemical analyses for drift loss measurement. Unfortunately, the results are never available immediately. It may introduce test uncertainty or even test miss-evaluation in case of, as an example, a filter contamination, without the possibility to run the test again. An alternate method using the measurement of the conductivity of the filter washing water is easy to perform on-site, gives immediate results allowing observing abnormal measurement. The paper describes the testing procedures and gives the limit of use to get accurate measurements. For the drift eliminator certification organized by EUROVENT in the Hamon lab during 2009 and 2010, both methods were used for evaluation of results. Some test on site has also used both methods. The paper will compare both methods in lab and on site.