Feel around on the inside of the fabric behind the dark patches. Does it feel wet? If it is (and you’re sure it’s not just sweat), it could be that water is soaking through and your jacket or pants need a new application of DWR.

A note about wetting out after heavy rain: Even new, hardshell jackets can wet out after prolonged, very heavy rain. So if you’re seeing dark, wet patches after a long time in a storm, it doesn’t necessarily mean you need a new coating of DWR. Do a little detective work to find out for sure. Once you take the clothing home and it has a chance to dry, squirt it with a spray bottle full of water to see if moisture beads up. If it wets out again, it’s time for more DWR.

Clean the Clothes First

Wash your garments before re-waterproofing them to remove body oils and old dirt. It’ll help the new DWR coating adhere better to the fabric. Outdoor retailers will try to sell you a detergent made specifically for technical outdoor clothing, such as Nikwax Tech Wash, but you can save your money and use a regular laundry detergent. I’ve been using regular, old Tide Free & Gentle detergent on my outdoor clothing for years, and it’s done as good a job. After washing, you’re ready to apply the DWR treatment. You’ve got two options here: wash-in or spray-on.

How to Apply Wash-In DWR

After years of relying on spray-on DWR, I’ve moved on to using wash-in DWR treatment—with a twist. From hiking through the rainforests of Hawaii to mountaineering in Alaska, I rely on my hardshell jackets and pants to keep me dry. Leaky rainwear in temperatures that cold can be dangerous, even fatal, so I’m very particular about making sure my hardshell gear is as water-resistant as can be.

Your best options for a wash-in DWR are Gear Aid ReviveX Wash-In, Grangers Repel Wash-In, and Nikwax TX.Direct Wash-In. The instructions tend to say you should wash them separately from your regular clothes in either a top or front-loading washing machine set to a warm water, gentle cycle, and dump the liquid into the washing machine.

I prefer to fill a bucket with lukewarm water, dump the detergent into it, stir it together, and then let the clothes soak in it overnight. Garments will often float to the top, so use something to weigh it down that won’t bleed color. I’ve usually got a spare bottle of Drano or Tide lying around, so I usually use that.

The next morning, toss the clothes into the washing machine or hand-wash them. Just keep your other clothes separate. Some DWR treatments instruct you to follow up by tossing the garments into a dryer set to a low-heat cycle to seal in the coating. Just check the instructions on the bottle of the stuff you’re using first.

Navigating a 12-hour day through an all-day whiteout in Alaska’s Denali National Park this May, my freshly re-waterproofed jacket shed ice crystal meltwater perfectly. Two months later on Mount Baker in Washington, the water resistance held up just as well. You can expect to get a season’s worth of use from one re-treatment. In the past, I’ve made the clarification that you can get your garment’s water resistance close to its original performance, but not exactly equal. After using the soak-and-wash method for this season, it seems that the water resistance on my Arc’Teryx jacket and pants are as good as they were when new.

How to Apply Spray-On DWR

For spray-on options, there’s Gear Aid ReviveX Spray, Grangers Performance Repel Plus Spray, and Nikwax TX.Direct Spray.