You know that sinking feeling when rain starts pouring and you realize your jacket isn’t keeping you dry anymore?
Whether you picked up a used Arcteryx from a resale shop or you’ve been wearing your favorite shell for years, there comes a time when you need to check if it still works.
The good news is you don’t need fancy lab equipment to figure this out. You can test your jacket’s waterproofness right at home using things you already own.
What Is Hydrostatic Head Pressure?
Before you start testing, you need to know what you’re actually measuring.
Hydrostatic head pressure tells you how much water pressure a fabric can handle before it starts leaking. The industry measures this in millimeters (mm).
Here’s what the numbers mean for you:
| Rating | Protection Level | Real-World Use |
| 1,500-5,000mm | Light rain | Short walks in drizzle |
| 5,000-10,000mm | Moderate rain | Daily commutes and light hiking |
| 10,000-20,000mm | Heavy rain | Serious hiking and outdoor work |
| 20,000mm+ | Extreme conditions | Mountaineering and harsh weather |
When you press against a wet jacket or wear a backpack in the rain, you create pressure. A jacket rated at 10,000mm can handle about 10 meters of water pressure pressing against it before water seeps through.
How Does Your Jacket’s Waterproofing Fail?
You might think your jacket either works or it doesn’t, but waterproofing degrades over time. The DWR (Durable Water Repellent) coating on the outside wears off first.
This makes water soak into the fabric instead of beading up and rolling off. Even though the waterproof membrane underneath might still work, the wet outer layer makes you feel cold and clammy.
Body oils, dirt, and repeated washing break down both the DWR coating and the membrane itself. Areas that get the most friction—shoulders under backpack straps, elbows, and cuffs—fail first.
The Home Testing Method
You can run a basic hydrostatic test with items from your kitchen and garage. This won’t give you laboratory precision, but it’ll tell you if your jacket still protects you or if it’s time for repairs.
What you need:
- A clear plastic tube (like aquarium tubing or a clean garden hose)
- A funnel
- Duct tape or zip ties
- A measuring tape or ruler
- Water
- Something to prop up the tube vertically
Setting it up:
Take your jacket and stretch a section of the fabric tightly over a table edge or chair back. Tape it down so it stays flat.
Attach your plastic tube vertically to something stable—a door frame, a ladder, or a tall stand. The tube needs to be completely straight up.
Seal the bottom end of the tube to your jacket fabric using duct tape. Make sure it’s watertight around the edges.
Start pouring water into the top of the tube slowly. Measure how high the water column gets before you see water coming through the fabric on the other side. This height in millimeters represents your jacket’s current hydrostatic head rating.
What Your Results Mean?
If water leaks through at 2,000mm or less, your jacket won’t handle much more than light drizzle. You’ll get soaked in any real rain.
Between 2,000-5,000mm means the waterproofing is compromised but might work for short periods in moderate rain. Anything above 8,000mm shows your jacket still has decent protection left.
Most quality shell jackets start their life at 15,000-20,000mm. If your test shows significantly lower numbers, the membrane has degraded.
Sometimes you can restore some protection by reapplying DWR treatment, but if the membrane itself is damaged, no amount of spray-on coating will fix it.
The Simple Alternative Test
Not everyone wants to rig up tubes and measure water columns. Here’s a faster way to check: spray your jacket heavily with a shower head or hose. Watch how the water behaves. Does it bead up and roll off? That’s good. Does it soak in and create dark wet patches? The DWR is shot.
Now press your hand firmly against the wet fabric from the outside while checking the inside. If you feel moisture coming through within 30 seconds, your waterproof membrane is failing.
Can You Fix a Failing Jacket?
Sometimes yes, sometimes no. If the fabric soaks up water but nothing comes through to the inside, you just need to restore the DWR.
Wash your jacket with technical wash, then apply a spray-on or wash-in DWR treatment. This brings back water-shedding ability.
But if water leaks through even when the DWR is fresh, the membrane has physical damage. Small punctures can be patched with seam tape or repair patches.
Larger areas of delamination—where the membrane separates from the fabric—usually mean you need a new jacket.
When to Trust Your Results?
Home testing gives you ballpark figures, not lab precision. Professional testing uses calibrated equipment in controlled conditions.
Your setup will have variables that affect accuracy. But for practical purposes, knowing whether your jacket works in real rain matters more than exact numbers.
Test multiple spots on your jacket, especially high-wear areas. One section might test at 8,000mm while shoulders under pack straps only manage 3,000mm.
This tells you where the jacket is vulnerable and whether it’ll work for your specific activities or needs more attention before your next outdoor adventure.
Frequently Asked Questions
How can I test if my used Arc’teryx jacket is still waterproof?
You can do a simple home hydrostatic test using a clear plastic tube and water to measure how much pressure the fabric can handle before leaking. Or, just spray it with a hose—if water soaks in instead of beading up, it’s losing waterproofing.
What causes an Arc’teryx jacket to lose waterproofing over time?
The DWR coating wears off from dirt, sweat, and friction, while the membrane underneath can degrade from age or heat. High-friction areas like shoulders and cuffs fail first.
Can I restore waterproofing to a used Arc’teryx jacket?
Yes—if water doesn’t come through to the inside, wash the jacket with a technical cleaner and reapply DWR spray or wash-in treatment. But if water leaks through the fabric, the membrane is damaged and can’t be fully restored.
What hydrostatic head rating means a jacket is still waterproof?
A rating of 8,000mm or higher means your jacket still offers good protection. Anything below 2,000mm won’t hold up in real rain and likely needs repair or replacement.
How often should I test my Arc’teryx jacket’s waterproofing?
Test it once a year—especially before a hiking or backpacking trip. Used jackets or older shells can lose waterproofing even in storage, so regular testing helps prevent surprises in bad weather.
