The ASTM D870-15 standard specifies specific implementation procedures for testing the water resistance of coatings using the immersion method. The main purpose of this practice is to evaluate the resistance of coatings to water immersion in order to predict their durability and performance in practical use. The test results can be used in the development of Coatings and Coatings systems, quality control, and specification acceptance processes. The method described in this standard uses relatively simple and affordable equipment, such as Glass beaker equipped with Stirrer, which is suitable for testing various coating materials. However, it should be noted that the data obtained in this practice is for reference only and cannot be directly used to simulate long-term exposure to water in the real environment.