1. Check the adhesion between the water inlet and the rubber body of the hot water bottle. You can turn the adhesive outwards by hand; there should be no cracks or peeling.
2. Check if the screw at the water inlet is stripped. Stripped threads will cause the hot water bottle to leak. Choose a hot water bottle with a smooth, clearly defined threaded cap.
3. Check the elasticity of the hot water bottle. Good elasticity indicates a higher rubber content and less filler. When purchasing, touch the hot water bottle; a thicker feel is better. Stretch the hot water bottle and release it; the easier it returns to its original shape, the better the elasticity.
4. Check the vibrancy of the hot water bottle's color. Vibrant colors indicate purer raw materials and stricter production process control.
5. Check for contamination. Since the hot water bottle comes into contact with human skin, there should be no color migration on the surface. A simple way to tell: Gently wipe the hot water bottle with a cotton ball and see if the cotton ball gets stained with color. The lighter the staining, the less color migration.
