I reckon that a Yabbie Straw is indispensible on many South West walks, but I take mine everywhere. You never know when it might come in handy. Essentially, it's just a durable flixible tube. In my case it is the overflow pipe from a new motobike battery that I didn't need. It is exactly the same as aquarium airline (so your best bet to get one is to probably buy 30cm of aquarium airline from a pet shop).
In South West Tasmania, everything is always wet, but there is often no creeks or lakes or any good water source. But there are small yabbie holes everywhere in the ground, amongst the button grass or other vegetation (on my last walk we saw no walk yabbie holes were the only water source we saw during the last two days). These always have a bit of water in them, and in many cases are full of water, and if you suck it out with a straw, it usually just seeps back in from the ground around, providing an excellent water source where there often appears to be no good water access. I've also used the yabbie straw to drink water from various tiny puddles including a boot print in the mud on a track where I was thirsty enough.
I'd never suggest that you could avoid having to ever carry any water at all on any track, but it certainly reduces the need to carry water. There's a limit to how much you can carry, when every litre adds another kilogram to the pack weight.
Here's another use of my Yabbie straw when it's been cold, as demostrated by my Dad:
- Yabbie Straw.jpg (74.47 KiB) Viewed 12539 times
I've no idea where the term 'Yabbie Straw' comes from, but I got it from my brother who's done a fair bit of walking. For all I know he made it up, but I really don't know.