SLICK FILTRATION TIP HERE!!
I use a 4L Sawyer Gravity system, our group is 2-4 hunters. We love this thing. Even if it was just me, I would use the 4L and use the clean bag as my hydration bag. Quick connects will allow you to leave the hydration bag in your backpack and fill it directly from the dirty bag.
Here's my *MAJOR* recommendation for ANY gravity filter-- pre-filter your water. This will keep your filter from getting fouled, even clear water has plenty of debris in it and if you are forced to drink from a really silt laden source this will device will pay for itself at once. Fouled filter can = ruined hunt.
The perfect, cheap ($12), light (2.1 oz), reuseable solution: Go on Ebay and search for: Industrial Diesel Filter Bag
Your will find a listing from seller, "dudadiesel", select the following drop downs:
Bag type- choose "Nylon Monofilament" these bags dry instantly and hold no water when you're done. Felt bags take forever to dry.
Size- choose 7"x16"
Micron- choose 10 micron
Use the bag by stuffing it into your dirty water bag, the large lip ring on the bag will remain outside your dirty bag. Then pour in dirty water to fill your bag. Once full, pull the pre-filter out, turn it inside out and give it shake. All the debris will fall out and *viola* you're good to go for the next time!
(note- I am not affiliated with, nor do I know dudadiesel).
Cheers!
JL