Start with two of the Backpacking Light MiniDrop Dropper Bottles. Fill one little bottle with A and and the other little bottle with the B part of the mix. Make sure to label the bottle, a permanent Sharpie is a good tool. I put the Black cap on the B part of the mix.
Actually, it doesn’t matter if these get mixed up, as long as you use equal drops of each. So, realistically they don’t need to be labeled, but I label ‘em anyway.
So, before I even leave the trail-head, I mix up equal drops in my even smaller dropper bottle. The Bozeman Mountain Works MicroDrop Dropper Bottle, the smallest size, and very cute. This will only take about 40 drops ( approx. 20 of A, and 20 of B).
Then when I get to a spot when I need to tank up the water bottle, I just use the pre mix.
HOW MANY DROPS?
The instructions say to use 7 drops of A and 7 drops of B for 1-liter of water. Before we proceed, those instructions were written by lawyers! So, let’s factor that into the equations.
Please be aware that drop sizes for any bottle are going to be dependent upon two factors: the viscosity of the fluid being dispensed and the design of the dropper tip.
Next: The BPL dropper bottles seem to have a different diameter opening than the Aqua-Mira dropper tip, so the drops are different sizes. The viscosity of the liquid may change slightly, and that would also effect the number of drops. Multiple variables, but here’s what I’ve found. If you put 14 drops (equal parts, A and B) into the tiny dropper bottle, you can only release 10 drops, then the bottle is empty. So, somewhere there is a discrepancy of the number of the drops.
That means - if you wanna follow the instructions exactly, adding 10 drops of the mix is correct, not 14. Got it?
But, remember, those rules were written by lawyers, and the instructions would allow you to treat raw sewage with confidence. If you get water from a running stream in the mountains, the need for following the exact instructions is ridiculous.
For me, I try and use as little as I feel necessary.
For a reliable water source, I won’t treat at all, I’ll just drink it un-treated.
But, for example, a lake in the Wind River Range that has a impacted campsite nearby, I’ll use 5 drops of the mix for about 2-liters of water. Approx. one quarter what the legal staff at Aqua-Mira recommends.
Maybe a little more, if there are multiple campsites, and a I’ll follow the instructions exactly if there are piles of sheep droppings all around the lake.
No good answer here, and if you get sick, don’t sue me!
But - fewer drops means less swimming pool taste.
HOW LONG WILL THE PRE-MIX LAST?
If it’s yellow, it is effective. The yellow will slowly disappear over time. ANd there are a lot of variables here, including temperature, light, oxygen. I’ve found if I make up a batch of mix, it’s used up in 24 hours. I’ve been told (by a representative of a certain company that makes a certain water treatment) that it’ll probably last a week, but 48 hours seems like a conservative amount of time to trust it’s effectiveness.
Again, no good answers.
Backpacking Light MiniDrop Dropper Bottles (2-pack)
Weight / 0.36 oz. (10.2 g) for set of 2
Capacity: 8 mL capacity (0.25 oz of water)
Bozeman Mountain Works MicroDrop PLUS Dropper Bottle (3-Pack)
Weight / 0.068 oz (1.9 g)
The MicroDrop PLUS Dropper Bottle performs one core function: to hold up to 130 or so drops of fluid (depending on fluid viscosity) in the smallest form factor possible, and tucks away neatly into one nostril.
Bozeman Mountain Works MicroDrop Dropper Bottle (3-Pack)
weight / 0.05 oz (1.4 g)
Capacity: 0.06 fl oz (1.7 g) of water, or about 40 drops