Water...

Above is my water system. I'll use it to filter, store, carry, and drink an estimated 1,200 liters of water. Here is how it works. Please read carefully, there will be a test at the end. 

The blue bag is for dirty water. It holds two liters and I have two of them. On top is the filter which screws on the bag. When I squeeze the bag, the pressure pushes the water through the filter and I store the clean water in the clear bag. I also two liters, and the one liter Gatorade bottle, which I use for drinking. When everything is full, I have a capacity of carrying 7 liters, 4 dirty and three clean.

The mug is used to scoop water out of shallow creeks or pools of water as well as for drinking hot cocoa or tea.

Water is very heavy, so I only carry as much as I need based on how far it is to the next water source. I usually carry about one liter for every 5 miles, plus an extra liter if I'll be camping between water sources. The extra liter is for cooking, washing, and brushing my teeth. The most I have carried so far is six liters.

Water is a big challenge for the first 700 miles of the PCT. There are sections of the trail where the next water source is 30 plus miles down the trail. Creeks, rivers and springs dry up, spigots get turned off for various reasons, and water sources like horse and cattle troughs can get very polluted or run dry. To help hikers there is a web based, crowd sourced, water report for the PCT. Hikers call, text or email updates on hundreds of established water location along the trail noting flow, volume, general clarity and any other details that might be helpful. I have an app on my phone that downloads a copy for offline use, and grabs updates when I have cell service. The report is very helpful in deciding how much water to carry. 

Keep calm and filter on!