Alex, All these comments are right on, I would just stress breaking out consumables into a seperate category as they will change significantly from trip to trip and change significantly within the trips (from beginning to end, and from water stop to water stop). But the gear in your base weight really won't change much based on length of trip. That's why it is your "base" gear weight. Now this weight will change depending on the weather to be encountered so when comparing weights and lists it is important to consider the weather.
Its not that water isnt counted. It is counted in your consumables weights (food, water, fuel) which is typically measured at the beginning of some typical trip distance (I use 2.5 days).
One more thing...a 5 oz water container is sacrilege around here:)