THE SIMPLE ANSWER: CARRY ENOUGH WATER TO GET YOU TO THE NEXT WATER SOURCE WITHOUT SUFFERING FROM DEHYDRATION; AND DO YOUR RESEARCH.
This is a great question and one I've heard echoed by women who have never gone backpacking. So whoever asked this, you're not alone. Carrying pails of water isn't an option, so how do you account for all the water you'll need while backpacking?
Carry two 1-liter light plastic bottles of water. I keep them in my backpack's side pockets and drink from one bottle until I finish it. I'll fill the empty bottle and treat it as soon as there's a viable water source. Since I use aquamira to treat water, it takes a minimum of 15 minutes until the water is potable (drinkable). I'll stay hydrated with that second bottle of water. So I always have one liter of water available and one getting treated.
Sometimes I carry a collapsable 1-liter water bottle if it's late in the season (which means water sources might be dried up), if the area's been in a drought, or worse, both. This gives me the ability to go for longer stretches without having to find and treat water.
I used to use a water bladder, but found that I never really knew how much water I had left because it was such a hassle to pull it out. I tended to be dehydrated. (Yikes!) I'm a lazy backpacker, what can I tell you? So this two bottle system's been working well for me. Easy. Convenient. Ultralight.
TIP: 1 liter of water = 2 lbs, so you don't want to carry a ton of water if you can help it.
Do your research. Check maps to see where the water sources are and call a ranger to find out confirm that those creeks/streams/lakes/rivers aren't dried up. They'll have the most up-to-date info.
Hope this helps! I hope you find abundant and refreshing water sources!