Step 6: Gear: Water
If you're not sure how much water you'll need, go ahead and take at least 4 1/2 liters. Your health and safety are too important to take chances, even if it means carrying more weight than you would prefer (each liter of water weighs about 2.2 pounds). Also, remember to bring the water you'll need to cook whatever you're cooking.
Start your trip with a full load of water, don't depend completely on fill stations or streams or whatever along your way: you may be dissapointed, and then, dehydrated.
And NEVER NEVER NEVER NEVER(!!!!) skip an opertunity to fill your canteen with clean water.
Also, you can invest in a filtration system and/or other purification system. Either just in case, or for a long trip with no clean sources of water.