I'm going on a 45min run today to test out my new running vest before my 3h long run tomorrow. I'll be loading it with 2x 500ml soft flasks and a 2L reservoir to see how it feels. I've never run with a vest before, but I need more fluids than I can comfortably carry in my hands for these long runs.
I got a 1.5L back reservoir and have been using it for my longer (15 km +) runs. I’m stunned by the difference proper hyddration has made. Recovery time after longer runs has been much shorter as well.
I've never tried running with a vest before either. I usually don't carry water at all but I almost never go over an hour. I imagine it would annoy me if the flasks were swinging around at all.
I very much prefer the front pocket vest to the backpack reservoir when running, it sloshes around a lot less. I also put about 1/8 tsp salt in each of the 500ml flasks for a little bit of electrolytes to prevent cramping on long runs.
You shouldn't have any sloshing if you suck all the air out. I'm mentioning this because to my surprise, a lot of people, even experienced runners do not realize that iscan option, and were used to running with their water sloshing around as they run. :)
I don't plan on needing all 3L of fluid for my 3h run either, it's just to get a feel of how it is to run with, I'll only bring the 2L reservoir tomorrow. But I will probably need all 3L for my upcoming 50k.
It's self-supported and just me going on a run and not an event, so there aren't any aid stations. I might loop around my home so I do the first 30k in one go and the restock for the last 20k at home.
If you go to the route of carrying all your water, you might try running 6 miles with 3 liters first.
Sometimes I include gas stations or groceries on self-supported routes to refill. Sometimes I buy Gatorade or bring my own Tailwind mix and add it to water. Filtering from natural sources is also an option.
On some solo 50ks I’ve left the house with no water at all, only a plan for how I would acquire it periodically along the way. Without a hydration bladder a hydration belt has been sufficient to carry my gear.
Went on a 25k with the full 3L to get a feel for it, and it felt absolutely fine. No discomfort by the end at all, so hopefully that carries through to the full 50k.
But planning the route along gas stations is not a bad idea, I'll see if there are any close by route I was planning.