PurePath
Dispatch №001 Building in public
A field journal  ·  Northern California

I couldn't find a soft flask that wasn't plastic. So I'm making one.

Medical-grade silicone body. 316L stainless collar. Threads onto any standard 42mm filter — Katadyn, Sawyer, LifeStraw. Lab-tested for leaching, every batch. I'm documenting the build from sourcing to shipping.

01 The Why

Why I won't drink from a TPU flask anymore.

I'm a 23-year-old CPA based in Northern California. I love trail running. Recently I started reading about what's actually in the gear I run with — the soft flasks, the bladders, the bite valves — and I couldn't unsee it.

Every soft flask on the market is thermoplastic polyurethane. Under sunlight and heat, TPU photo-oxidizes. It leaches VOCs and microplastics into your water. The "plastic taste" everyone complains about isn't in your head — it's the sensory signal of what's already in your bottle.

So I cap my regular runs at two hours. About ten miles. I'd rather run four-hour days in the Sierras, but I don't want to drink from a TPU flask, and stainless bottles don't fit in a vest or thread onto a filter. The category forced a tradeoff I refuse to accept.

PurePath is what I'm building because no one else has. It's not vaporware — I'll show you the supplier emails, the rejected prototypes, the lab reports, the failures. If you want one, get on the list. If you just want to watch, that works too.

02 What's actually different
/ 01

Zero plastic touching your water.

USP Class VI platinum-cured silicone body. 316L surgical stainless collar. 100% silicone bite valve and gasket. No TPU, no PE, no painted logos, no plastic threads.

/ 02

Standard 42mm thread.

Threads onto every major trail filter — Katadyn BeFree, Sawyer Squeeze, LifeStraw Peak. No proprietary lock-in. Use the gear you already trust.

/ 03

A leaching report on every batch.

Third-party GC-MS testing on samples from every production run. Results published publicly, not buried. The certificate of purity is real, not marketing copy.