Products need to be tested to a column pressure of 5,000 millimeters to be considered waterproof for basic, everyday activities. More technical outerwear, including products created with Gore-Tex, can range from 15,000 mm to 20,000 mm in column pressure. In other words, they’re definitely waterproof.

While PVC and PU rainwear are effective in repelling water, they aren’t necessarily breathable. Technologies like Gore-Tex or Polartec’s Power Shield, on the other hand, offer more breathability. Gore-Tex is a porous membrane made of expanded polytetrafluoroethylene (or ePTFE), and “the pores are small enough that they don’t let water drops in, but they allow vapor to move out,” Hadravska explained. Here’s where things get a little technical. A textile’s level of water resistance is measured in column pressure. Imagine a one-inch tube that’s sitting on top of the fabric, and it’s filled with water. At one point, the column is high enough that there’s so much pressure that the water will actually come through the membrane. That’s the number you need to look out for in terms of grading waterproofness.Various fabrics and assembly techniques can be used for waterproof and weatherproof clothing. Polyurethane and PVC, a type of vinyl, have been go-to materials for years ― think the classic yellow fisherman’s raincoat ― while innovations like Gore-Tex, a material often employed in technical outerwear, are extremely effective in repelling water.

Whichever method you use to wash your coat, make sure you hang it up to dry. It could be outside or in a room where you'll get plenty of ventilation. This will help you avoid having an unpleasant mildew smell on your coat.