2 .Inflatable method: seal the test shoes and openings, and fill the air into the water quantitatively, so that the distance between the water surface and shoes (boots) is less than 75mm. After a certain period of time, there are bubbles forming on the surface of shoes.

3. Immersion method: Test shoes and boots into the water, so that the distance between the water surface and the shoe opening is less than 75mm. After a certain time of immersion, take out and check whether there is any water penetration into the shoes.