Depending on how much weight you want to whittle away, one way to do it is leave the 1 qt Nalgene bottles and switch over to some soda bottles or maybe a Gatorade or Snapple ice tea bottle. All of them are lighter than the typical Nalgene and I've never had a problem with leakage as long as the lid is on properly. You might even consider carrying three 20 oz. soda bottles with your water. You'll end up with more water than in two 32 oz. Nalgenes and carry less weight.
That's all for now. Take care, good luck on cutting down your weight (I'm in the middle of that now for an upcoming trip) and until next time...Be well.