Toilets could be designed with a flush tank that has two levels - one for liquid waste and the other for solid waste. If level (2) flushes 3 galons of water, level (1) could be designed to flush half of that as liquid waste does not need too much water to flush.
This would save millions of gallons of precious water everyday in every home around the world.
Reward: not sure. but if this productized, it would help save precious water (which we take for granted) and save our planet.