Test your rainwear by sprinkling or spraying some drops of water on its exterior. Does it bead up and roll off? Your DWR is in good shape. If you give the fabric a single strong shake, does most of the moisture fly off? Ditto.

If, however, the water sits on the fabric and that section begins to darken slightly, water is making its way to the fibers and wetting the fabric. It's time to revive your DWR.

Good news: DWR coating does not impair your jacket's breathability. Rather than coating a textile's entire surface, DWR coats individual fibers, leaving the space between the fibers open for breathability.