Are Dry Bags Fully Waterproof? Roll-Tops and IPX Ratings Explained

A good dry bag, closed properly, is genuinely waterproof: rain, spray, splashes and a dunking won’t get in, and the trapped air means it floats. What no roll-top bag is designed for is long, deep submersion — for a phone that’s going underwater, use a certified waterproof phone case inside the bag as well.

Watch: IPX6 and IPX8 explained in two minutes, and what our bags and phone case are built for.

How does a roll-top dry bag keep water out?

The bag itself is a welded, waterproof tube — the only way in is the top. Rolling the top at least three times and clipping it creates a seal water can’t work through, and traps air so the bag floats if it goes overboard. The material matters too: thin bags get pinholes. Ours are made from premium-grade 500D (denier) waterproof PVC, approx. 0.5mm thick, which is why we can back every bag with a 5-year guarantee — and why UK International Search and Rescue teams carry them on real deployments.

What do waterproof ratings (IPX) mean?

Rating	Means	In practice
IPX4	Splash resistant	Rain and spray only
IPX6	Powerful jets	Heavy weather on deck
IPX7	Immersion to 1m for 30 min	Survives a dunking
IPX8	Continuous submersion	Safe underwater (to the depth the maker states)

IP ratings are lab certifications, and our bags are IPX6 rated — tested against powerful water jets from any direction. That is the standard that actually matters on the water: rain, spray, waves over the deck and a capsize.

So when we say a bag is 100% waterproof, we mean the bag itself — the body is welded with no seams to leak, and rolled three times and clipped, the top seals. Water does not get in, and the trapped air means it floats. What the rating does not mean is that you can leave it underwater: continuous submersion is what IPX7 and IPX8 describe, which is why the phone case is separately certified to IPX8. We hold the supplier’s test certificate for the IPX6 rating.

How do I make sure my dry bag doesn’t leak?

• Don’t overfill — leave room for at least three full rolls at the top.
• Roll away from the opening, keep the folds neat, clip firmly.
• Squeeze most (not all) of the air out first — a little air keeps it afloat.
• Check the inside after gritty beach days; rinse and dry before storing.

What about my phone?

Belt and braces: every Ultra Dry bag comes with a waterproof phone case, and our large IPX8-certified phone case is the one to choose if the phone itself will get wet — it’s certified for submersion and still lets you use the touchscreen. Pop it inside a 10L dry bag and your phone has two waterproof layers between it and the sea.