How to Renew a Jacket's Water Repellency. Waterproof jackets, pants and other garments can be real lifesavers when the weather gets wet and windy. Though their ability of being waterproof never fades, their water repellency will, which can make them susceptible to water logging in heavy weather, leaving you feeling cold and clammy.
Determine what kind of material from which your garment is made. If it's not written on the outside of your garment, you can find it on one of the interior tags.
Purchase a bottle of compound that will renew the jacket's water repellency. McNett and Nikwax both make products that are easy to use and can be washed in or sprayed on after washing.
Wash your garment following the manufacturer's instructions. Gore-tex and other similar materials usually ask that the garment be washed in warm water on delicate, but make sure to check before tossing it in the machine.
Wash your garment again, if it was especially funky or dirty. Camping, backpacking and mountaineering trips can all do strange things to outerwear, so don't shy away from a second washing if your garment needs it.
Spray on the repellency renewer evenly and try not to use more than you need to coat the garment. Regular sized bottles of the renewer typically only have enough liquid to renew one or two garments, so use it sparingly.
Dry your garment in an automatic dryer, as this will make sure that the compound "sets" and that the water repellency is restored to its factory strength.