They can't carry much and I couldn't carry the water really for 2 adults and 2 kids + stuff and food...
How common is water in your area? I would carry a little, but at least in my area water is not a problem to find. Lake Erie is a few miles away and there are rivers & ponds all over. With a water filter you can make clean water faster then you can drink it. Also boiling is an option with a pot and a wood stove, or a Kelly Kettle or Thermette.