Browsing Facebook running groups, one of the most common questions that people have is when to bring water on a long run. For me, personally, the answer depends on how I'm feeling on that given day, the weather conditions, what the designated effort is for the workout (easy versus faster) and my hydration and fueling level up to that point.
For road runs, I default to carrying a handheld water bottle for pretty much anything over 90 minutes. With only a single bottle, I carry at least 10.5 ounces or more (I have 14-ounce and 16-ounce bottles, as well) of water with electrolyte drink mix.
When I run trails, I have my vest with two 16-ounce bottles, one with water and the other with electrolyte mix. I prefer bottles over a bladder for long runs for the reason of having two different liquids, for ease of access and refilling, and the weight is distributed in the front and separated as opposed to the 2-liter bladder that goes on my back. I will use the bladder for all-day adventure runs, though, but usually won't refill it (I'll refill the bottles in those cases).
My preferred electrolyte drink is Tailwind for the subtle flavor profile despite having a high level of carbohydrates (dextrose and sucrose), a comparatively high calorie contest (100 calories per scoop compared to 50-70 for other hydration mixes), and the electrolyte blend using magnesium citrate, potassium chloride, calcium carbonate, sodium citrate, and sea salt.
The flavor profiles range from Naked (unflavored, think SweeTarts candy), Raspberry, Lemon, Mandarin Orange, Tropical, and Colorado Cola (the company is based in Durango). Some flavors are caffeinated, others are not so there are options.
Personally, I like to mix and match flavors. Most recently, I mixed the raspberry and lemon and it wasn't too sweet but also gave me the electrolytes that I needed to complete my long run without having to take a gel or solid food with me.
Tailwind isn't a replacement for the supplemental fuel sources like gels, but it's a handy tool to have in the arsenal for distance training, especially during the warmer weather when trying to eat anything gooey or sticky or substantial isn't going to settle right.
One of my favorite things about running long distances is the experimental aspect of it. There is a risk, but there's just as much of a reward of figuring out and fine-tuning race-day nutrition and hydration.
South Sound Running has two-scoop sleeves available in a variety of flavors for such experiments or larger quantities are available, as well, if you find a flavor that works best.