Are Dry Bags Fully Waterproof? Roll-Tops and IPX Ratings Explained
3 August 2026
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.
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 7.5mm pure-grade polymer, 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, mostly used for electronics and cases. Roll-top dry bags generally aren’t IP-certified — their job is keeping kit dry through rain, waves and capsizes, and a quality one does exactly that.
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 in the box, 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.