What is waterproof?

What is waterproof?

The term ‘waterproof’ is used quite often in the outdoor sphere, but what does this actually mean, and how does this sometimes mislead consumers as to what their garments are actually capable of? We’d like to fully explain, and to bust some myths surrounding waterproof fabrics in the process.

Let’s start by saying that ‘waterproof’ is, technically speaking, nothing more than outerwear that is extremely water-resistant.
One way to test how water-resistant a fabric is, is by conducting a static-column test.

• Static-Column Test & How it Works:

Static-column testing is the most widely used waterproof test. A 2,54cm-diameter tube stands vertically over a piece of material. The tube is filled with water, and the water’s height in millimeters when leakage begins becomes the waterproof rating. A piece of fabric that can withstand 20, 000mm of water pressure which will have a rating of 20, 000mm or 20K.


What do these ratings mean for real-life situations when you’re caught in a downpour? Here’s the general gist:

  •  0: Not waterproof at all

Think sweaters, cotton T-shirts & stockings. Softshell jackets like the K-Way Men's Felixx and the K-Way Women's Mira are not waterproof. 

  •  1-1K: Rain resistant, but not rainproof

Think cellphones, basic softshells & DWR (Durable Water Repellent)-treated flannels like the K-Way Men's Jetstream Shell Jacket  or the K-Way Men's Printed Arc Jacket.

  •  1K-5K: Rainproof, but not under pressure

Think leaky umbrellas & coated softshells like the K-Way Men's Torrential Rain jacket or the K-Way Women's Misty Rain Jacket.

  • 5K-20K: Generally waterproof, unless subjected to considerable pressure

Most high-end bike-messenger bags and rain jackets like the K-Way Men's Franklin or the K-Way Women's Bonnie Rain Jacket.

  •  20K-40K: Guaranteed waterproof during extended pressure and shallow submersion

Think high-end mountaineering jackets like the K-Way Men's Kilimanjaro Shell jacket and waterproof watches 

  • 40K+: Non-porous materials that will fail structurally before leaking

Think garbage bags & rubber galoshes. These materials are waterproof, but they don’t breathe at all. If worn as outerwear, they’ll make you sweat profusely.

How does construction affect waterproofing?

In short: GREATLY

Taped Seams

There's no point in springing for a high-tech waterproof breathable membrane if water can seep through past the stitching.

Welded Seams

Welded seams join panels of fabric via gluing or ultra-tech sonic bonding for a seam that's stretchier and less bulky than a taped seam and significantly more resistant to water pressure.

PU Laminates

PU laminates move moisture via an absorption-diffusion-evaporation process.


This is the same stuff used to coat non-stick frying pans. PFTE membranes work causing water to bead and roll off.

DWR (Durable Water Repellent)

This polymer is applied to virtually all face fabrics (i.e. a garment's outermost fabric). It penetrates the face fabric's fibers and causes water to bead up and roll off.


Denier refers to a fabric's fiber density.


Ratings offer a vague notion of waterproof protection, but understanding construction is a much better tool for comparing and choosing outerwear.

2L: A 2L (two-layer) garment consists of a face fabric bonded to a waterproof breathable membrane.

  •  Pro’s: 2L pieces are lightweight, breathable, and packable. 
  •  Cons: They leave the waterproof breathable membrane vulnerable to abrasion and soiling. A 2L jacket may be an excellent choice for you if you’re not too concerned with long-lasting waterproof protection or you’re very concerned with packability. Compare a 2L garment to a hardback book that’s missing one of its covers.  An example of this is the K-Way Men's Torrential Rain Jacket.

2.5L: 2.5L garments protect the membrane with a partial protective spray or coating.

  •  Pro’s: They’re a good compromise between 2L & 3L. 
  •  Cons: A 2.5L might be a good choice for you if you’re concerned about both packability and waterproof durability. Think of a 2.5L garment as a book with one hardback cover and one paperback cover. 

3L: 3L garments consist of a face fabric bonded to a waterproof breathable membrane that’s backed with a protective scrim.

  •  Pro’s: They’re extremely durable. 
  •  Cons: They’re generally thicker, stiffer, and less breathable. A 3L jacket might be a good choice for you if you plan to use it heavily and waterproof durability is your main concern. Think of a 3L jacket as a hardback book. Jackets like the K-Way Kilimanjaro Men's Shell Jacket is 3L garment.

How to care for your outerwear:

Step 1:

Wash it
Why? Washing your jacket removes oils and grime that can compromise the waterproof breathable membrane. Try the Storm 300ml Twin pack which includes a wash and proofer. 

Step 2:

Dry it
Tumble drying helps redistribute DWR treatment, restoring your garment’s water-resistance.

Step 3:

Re-DWR it
Repeated wear and washing will eventually deteriorate the face fabric’s DWR treatment. Try the Storm Waterproof 300ml Spray.