I believe some distinctions ...

I believe some distinctions are necessary here. Statistically one human being needs to consume approximately 2.5 L of water per day. However if you add in the minimum amount of water it takes to grow the food to feed that person the number suddenly pops up to 1500 L per day. As we work on solving the water scarcity problem, my group has already realized that creating highly water efficient closed loop systems that include if wastewater reuse can meet all of the requirements for safe drinking water, sanitary services and in the process add another source of animal or fish food. With this system it could be possible, just guessing to get the water needs for sustainability down in the 500 L per person range. Of course this is definitely a systems approach that integrates recipes for ultra-water efficient farming, adequate white water rationing and drip irrigation systems for the farmer members of the community and ideally use of wind and/or solar energy to allow the self-sustainable group to refrigerate and process the produce they are able to grow once they are taught how to optimize the output from their land allotment. At this moment our world and global economy is much closer to a water shortage induced catastrophic outcome than anyone even wants to imagine. The good news is that over the past 10 years we have developed the tools to radically change the way we use water. Now are challenges to teach the people who have brought the tools into commercial of viability how to also consider them in terms of the end user of the electricity and heat products. A reasonably small system can keep 12 or 500 people well fed, well-nourished, water healthy on both safe drinking water and proper sanitation and actually increase the impact and income of the village group substantially. In the areas of the world where people are making less than two dollars per day properly designed systems that I am currently calling islands of sustainable self-sufficiency, could set a framework for these people to multiply their income by a factor of five within 3 to 5 years. This system does require that the individual solution thinking we been caught up in gets included in community thinking because to create this true sustainability we must create a balance which will require that we provide enough energy to meet the needs, manage the way the energy is used relative to water and farming very clear carefully, and design the village in a way that a reasonably well-designed vertically integrated organization that operate. One thing I've become quite passionate about is that sustainability will come about much quicker if we take knowledge and demonstration with us and spend the time to train the villagers to understand their eco-village, install equipment that can be maintained by people in the village we can then end up with solutions that work extraordinarily well for the rural people. A major barrier to the people who can have the biggest impact on our planet and our global economy is going to require a completely new paradigm from the development banking community and the industrials and major multinationals that sponsor these efforts. This situation I'm describing is likely to take about five years before the people who are now too poor to be economically significant will start becoming a significant part of this new bottom-up economic structure. But for the companies who have the foresight to realize that I am describing a 3 billion person market should be able to get the fact that we need to make a little investment to get them out of the ditch and upwardly mobile. This needs to be done as a business, and based on these people achieving improving economic and food sustainability which will then start adding disposable income.