Waterproof vs Water Resistant What's The Difference

There are few things more frustrating than arriving somewhere and realizing your gear is soaked through. That’s why choosing the right bag is super important. But finding that right bag can be trickier than we think: some bags say they’re waterproof, others say they’re water resistant, and you might not know what either term really means, let alone what you need.

 

Don’t worry. We’re here to help. We’ll explain the difference, look at all the variables, and give you some tried and true recommendations, so you can nail your bag of choice.

 

What's the difference? 

The difference between waterproof and water resistant seems obvious. It’s right in their names. Waterproof means water won’t get through the bag. Water resistant means the bag will hold up against water but, at some point, water will get through.

 

That’s all true but all too simple. There are degrees of water resistance and waterproofness. So, to know what you need, you need to know how everything works.

 

Let’s dive into the differences.

 

What Does Water Resistant Mean?

Water resistance comes down to a bag’s materials and how those materials are put together. If any element of the bag can let water in, then it’s no longer waterproof. But it can still be pretty water resistant.

 

The Material

 

Let’s start with the fabric. The most common fabrics are nylon, polyester and cotton. These are measured in Denier. One yarn of the material is about one denier. The higher the denier count, the heavier the yarn.

 

So if your bag is made of 400D nylon, then each of the fibers is made up of 400 yarns of nylon. And so you'd think the more dense the material, the less water will get through, right? Not necessarily true.

 

600D nylon will repel water better than 1680D nylon.  The super high Deniers, although thicker in fibers, actually have larger gaps (but I digress, we could write a whole post on Denier!).

 

So, even when the material is woven tight, water can still seep through. Water molecules are small, after all. If the water pressure is high enough — that is, if it’s exerting enough force on the bag — water could make its way through the pores in the material.

 

So you really need something with a protective backing or coating.