For many people, this essentially limits the length of your trip to two or three nights. If you're planning a longer trip and the weight of your pack is stretching your physical abilities, cut out weight in other ways instead of reducing water supply. Shop for a super-lightweight tent and sleeping bag. Go with the lighter but perhaps less comfortable sleeping pad. It might be tempting to leave your tent home to save weight, but a tent can be a life-saver if bad weather blows in.
Food presents a special challenge.
This means you have to add to your water supply or use alternative foods that don't require extra water. This might seem like heresy to backpacking gourmands, but one alternative is to take the no-cooking option. Prepare evening meals in leakproof containers or make sandwiches. Plan on snacking for breakfast and lunch. This essentially means snacking all the time instead of cooking.