If you think you may have moisture in a fuel tank,pickup tank or storage tank,there is a product made to check this! What I use is a paste like product, put small amount on a steel rod or stick,slide down into bottom of tank. Pull out and paste will show different color if moisture is present! Any fuel supplier should have this. If any interest, I'll try to get a name. Have had it around for a long time so may be no name on container. jps