Depending on how far the source is and you may have to carry more.
True that! Water sources, near and far (which is more than likely, closer than your origin - home ) within your backpacking area/route should be part of the plan. My troop and I backpacked 80+ miles for 10 days in the Bob Marshall Wilderness and plotted major water sources throughout ... and all I have was 20 oz nalgene bottle and my filtration system.
I voted for my "FREEDOM", "GUNS", and "MONEY" - keep the change - UNK.
"I am always proud of my country!"
"Leadership Rule #2: Don't be an edited." - Maj Gen Burton Field.
While hunting the high country, water can be scarce up on the high ridges. Over the years I've learned that I need to have a couple of quarts with me, and a filtration system to fill 'em up again as the opportunity arises. I'll take some empty quart bottles or a collapsible gallon water bag/jug and fill them when I get to where I'm establishing my base camp.
I like the camel-back systems too. For a filter I use the little MSR/Sweetwater pump. It's proven very dependable and easy to use.
I use a Katadyn Hiker PRO Water Filter. It comes with a quick connect that hooks into your mounthpiece and pumps the water straight into the bag. Very easy and quick!
By the way, I recently switched out my old camelbacks for the new cabelas brand, which is a much stiffer plastic that doesn't get folded over and cut the water off, and there is NO plastic taste whatsoever. I usually fill the 3liter bag and carry a small plastic bottle. I do add some powdered gatorade/powerade mix after a couple days out just to break up the crickwater taste. They work good also to mask the iodine taste if that is what you are using.