Most backcountry water kits are an accident of history. You buy a filter, it comes with a bag, the bag threads onto some bottles but not others, and over a few seasons you end up carrying a drawer's worth of adapters and spare caps that half-fit each other. The fix is not a clever gadget. It is picking one interface and building everything around it.
Igneous builds around the 28-410 bottle thread, the same neck standard used on a Smartwater bottle and on most single-use drinking bottles sold across the Americas, Europe, Australia, China, and Japan. One thread runs your drinking cap, your filter connection, your gravity setup, and your backcountry hygiene. Fewer adapters, fewer failure points, and a replacement bottle you can buy at almost any gas station on a resupply.
This is the hub post for how that system fits together. Each piece has its own deep dive linked below.
Why one thread standard changes the whole kit
The number 28-410 describes a neck: roughly 28 mm across, with a thread profile (the "410" finish) that has become the de facto convention in lightweight backpacking. Because so many filters, caps, and bottles already speak it, standardizing on 28-410 means the parts you own tomorrow will still talk to the parts you own today.
A wide-mouth bottle like a Nalgene is tough and easy to fill, but its opening does not accept most filtration accessories, so you end up filtering into one container and pouring into another. A 28-410 bottle removes that transfer step: the filter threads straight onto the bottle. If you want the full compatibility breakdown, which filters seal, which do not, and why, we cover it in our guide to NOBO threading and filter compatibility.
The bottle at the center of this is the NOBO Bottle, a rigid unpigmented HDPE bottle with a silicone-sealed cap on the 28-410 thread. It has been shipping since 2025, so the old "when it's available" caveat is gone. If you want the reasoning behind the material choice, start with the material science behind the NOBO, and for why the cap seals the way it does, see how the NOBO is designed to reduce microplastic exposure. And if you are running a disposable bottle in the meantime, we wrote an honest answer on how long that is actually a good idea in is it safe to reuse a Smartwater bottle.
Flat-gasket seals beat inside-the-neck seals
Here is the one piece of design detail worth understanding, because it explains most of what follows. There are two common ways a cap or accessory seals against a bottle.
The first pushes a plug or O-ring down inside the neck and seals against the inner wall. That works, but it is sensitive to how the neck was molded: bevel quality, ovality, small nicks that build up with use. Change the bottle a little and the seal changes with it.
The second presses a flat gasket down onto the top rim of the bottle. The inner diameter of the neck stops mattering. This is how the Sawyer Squeeze, the Platypus QuickDraw, and every Igneous cap seal. It tolerates a wider range of neck finishes, it keeps sealing as the bottle ages, and the gasket is visible and replaceable if it ever gets damaged.
Quick field test: if an accessory threads on and clamps down on the top rim of the bottle, it will seal reliably. If it relies on a stem or plug pushed down inside the neck, expect the fit to vary bottle to bottle.
The pieces
Cap & Tether
The Cap & Tether is the everyday drinking cap. A rigid PA12 body carries a silicone flat gasket that seals on the bottle's top rim, and a TPU 95A tether keeps the cap attached so you stop losing it at water sources. It weighs 7 g assembled, and it fits Smartwater 700 mL and 1 L bottles, LifeWTR 1 L, the NOBO Bottle, and other 28-410 bottles.
- Materials: PA12 body, silicone gasket, TPU 95A tether
- Gasket: 2 mm thick, 18 mm ID x 28 mm OD, mechanically captured (no adhesive)
- Weight: 7 g
Bottle Cap Bidet
The Bottle Cap Bidet uses the same 28-410 thread and the same flat-gasket seal, with a single-jet nozzle in place of a drinking spout. Because it threads on and seals on the rim rather than wedging into the neck, it sits more securely than insert-style bidets. It is an all-PA12 body with a silicone gasket, so it shrugs off aggressive cleaning if you ever need to disinfect it. For the full case on why water beats packing toilet paper in and out, see the case for leaving toilet paper at home.
Hang System
The Hang System is the gravity-filter piece. Rather than trying to mate directly to a filter, it suspends the dirty bladder you already own, which then feeds your filter of choice. A PA12 cleat with a handle lets you tension or release the line one-handed, even with cold fingers.
- Cord: 1.8 mm nylon, 1 yard, roughly 250 lb tensile with a recommended working load near 100 lb
- Weight: 7 g total
- Works with: any looped bladder (CNOC Vecto, Platypus, HydraPak and similar)
Keeping the load path bladder-first means you stay inside each manufacturer's intended filter connection and avoid a pile of couplers. If you are still deciding on the filter itself, our comparison of the Platypus QuickDraw versus the Sawyer Squeeze covers the tradeoffs. And once you own one, keeping the filter flowing is a five-minute skill; our guide to backflushing a Sawyer Squeeze walks through it.
How it all works together
- Day hikes: run the Cap & Tether alone. Cap security, nothing else to think about.
- Overnights and thru-hikes: carry all three. Fill a bladder at the source, hang it in camp to gravity-feed, and thread on the bidet when you need it, all on the same thread standard with no specialty adapters.
- Travel and resupply: because 28-410 is everywhere, a compatible replacement bottle is a gas-station purchase away. That is one fewer spare to carry.
Care and maintenance
- Cap & Tether: soap and water for routine cleaning; dilute unscented household bleach for tougher jobs. Isopropyl alcohol is fine for quick wipe-downs. Avoid strong solvents like acetone or MEK, which attack elastomers. Air-dry before storage.
- Bottle Cap Bidet: rinse after use. If contamination is a concern, flush with dilute bleach or 3% hydrogen peroxide, then rinse with clean water. No disassembly needed.
- Hang System: wipe the cleat and line as needed, and let the nylon cord dry fully before long-term storage.
For keeping the bottle itself clean, from a quick rinse to dealing with mold or funk, we wrote a full HDPE bottle care guide. And if you carry your bottle into the tent on cold nights, read our safety guide to using a water bottle to warm your sleeping bag before you fill anything with hot water.
The short version
Pick one thread standard and the whole kit gets simpler. 28-410 is the one the backpacking world already settled on, so it is the one worth building around. Drinking, filtering, gravity, and hygiene run off the same interface, the flat-gasket seal keeps working as parts age, and a replacement bottle is available almost anywhere you resupply. Less to carry, less to lose, less to go wrong.
