top of page
anchorheader

Understanding water column ratings: How waterproof is your jacket?

Sep 3
2 min read

If you want to stay dry on your next outdoor adventure, there’s more to consider than just color and fit when buying a jacket. One often-mentioned yet rarely explained term plays a key role: the water column. But what exactly does it mean—and how much is enough for your activity?


What is a water column rating?

Imagine placing a pipe vertically on your jacket material and filling it with water. The water column rating tells you how high the water can rise in this pipe before it starts to seep through the fabric.


This is measured in millimeters: 1,000 mm is roughly the pressure of light rain, while 10,000 mm and above means your jacket will keep you dry even in heavy downpours. Legally, materials with 1,300 mm or more can be called "waterproof," but for outdoor use, that’s usually not sufficient.


Waterproof, water-repellent, or water-resistant?

These terms may sound similar, but they describe different levels of protection.

  • Water-repellent means the material can withstand light showers or drizzle—but that’s about it.

  • Water-resistant offers a bit more protection but still isn’t fully waterproof.

  • Waterproof means that even in sustained heavy rain, no water will penetrate—provided the jacket has at least a 10,000 mm rating.


Although 1,300 mm qualifies as waterproof by law, real-world outdoor use often demands much more.


Depending on the activity, your water column requirements will vary.


Recommended water column ratings by activity:

  • Hiking & everyday use: 5,000 to 15,000 mm

  • Cycling: 8,000 to 20,000 mm

  • Mountaineering & trekking: 10,000 to 20,000+ mm

  • Skiing: 10,000 to 20,000 mm


What to look for when buying

The water column rating alone doesn’t guarantee you’ll stay dry. Other features matter just as much.


A high rating is only part of the picture. The overall design quality plays a major role. Look for sealed or taped seams—water always finds the weakest point.


Even the best rating won’t help if the seams are poorly finished. Material choice is also key: durable ripstop fabrics withstand wear and tear longer, while stretch elements improve freedom of movement.


An adjustable hood and hem add protection against water and wind. And don’t forget breathability—because if you’re sweating on a climb, you don’t want to get soaked from the inside out.



Comments

bottom of page