Rain Happens: How to Tell If Your Bag Can Handle It

Almost every bag we carry—whether it’s a storage pouch or a backpack—has a chance of meeting water. Maybe it’s a sudden rain shower, a spilled drink, or that one time your bag decided to take a nap in a puddle. But how do you actually tell how waterproof your bag is?

Instead of guessing, the world has a neat way to measure this: something called hydrostatic head (mmH₂O). Sounds fancy, right? Think of it like this:

imagine standing a tall glass tube full of water on top of a piece of fabric. The higher the water column, the more pressure it puts on the fabric. The moment water starts sneaking through, you check the height of the water. That number, in millimeters, is the fabric’s waterproof rating.

 

For perspective:

500 mmH₂O = only half a meter of water. Not much of a challenge—expect water to seep through quickly. 

2000 mmH₂O = two meters of water. Good enough to block a solid rain shower.

10,000 mmH₂O = ten meters! That’s hardcore waterproofing—ready for downpours and maybe even a swim.

 

AWORKZON’s Easy-to-Read Waterproof Grades

Technical numbers are useful, but who has time to memorize water columns? That’s why AWORKZON created a simple grading system:

1. Grade I (Non-waterproof |<500 mmH₂O)

Dry environments or light/short-term moisture exposure, such as indoor use or inner dividers inside an outer bag.

 

2. Grade II (Basic Waterproof |500–2000 mmH₂O)

Humid environments or short-term splashes, such as daily commuting or travel.

 

3. Grade III (Advanced Waterproof | 2000–5000 mmH₂O)

Damp or splash-prone environments, suitable for extended outdoor use.

 

4. Grade IV(Extreme Waterproof |>5000 mmH₂O)

Designed for heavy rain or even underwater use, ideal for extreme conditions or expeditions.

 

The Hidden Side of Waterproofing

Here’s a secret: even the most waterproof fabric can fail if the bag itself isn’t built right. Tiny needle holes from stitching can become water highways. That’s why truly waterproof bags often use taped seams, seamless heat bonding, waterproof zippers, and roll-top closures. In other words: it’s not just the fabric, it’s the whole construction that keeps your gear dry.

So next time you’re checking out a bag, remember—it’s not about whether it looks waterproof, but whether it’s ready to laugh in the face of a downpour.