How can water penetrate into the inside of a waterproof/water repellent/breathable garment?
In general, waterproof/water repellent/breathable garments have stitching that is sealed with seam sealing tape on the inside so that penetration does not occur. Therefore, if there is “water penetration” it can mean that water is seeping through the stitching and not necessarily through the fabric. This can occur if seam sealing tape has been damaged or even unknowingly altered in any way.