By carefully selecting when water is used, and how much, we can certainly reduce our dependence on this precious natural resource. This is something that is mandatory for a place like the Mojave National Preserve when designing for cleaning, particularly bathing. When the average rainfall is around 4" every year you must collect only as much as needed to reduce the amount of built space that would take up the landscape. In order to reduce this square footage by enough you must use creative ways of reducing water use, such as recycling greywater, reducing cleaning times, using low-flow technology, etc. These images show the process that I used to reduce the amount of surface area needed for a person to survive for a single day with minimal water use. This water use includes potable drinking water, bathing, and even the required facilities of toilet and sink.
The first thing I did was calculate the amount of gallons of water were needed for this one person space per day. This lead to a 10-minute shower at 0.7 gallons per minute and a moderate amount of potable water for a desert environment, 2 gallons. This left me with 9 gallons per day, but also a very large surface area to collect that amount of water.
Secondly I reduced the amount of time for the shower as well as spread the potable drinking water to the three separate nodes that I am designing for this trail/process.
The three nodes would be able to collect enough water for 0.5 gallons of use per day from each node. This would lead to a reduction of weight for the person to carry through the trail, as well as disperse the surface areas to these different nodes.
Thirdly I ended up adding a toilet at 1 gallon per day use, and a sink at 0.5 gallons per day use, while also reusing the greywater from the shower and the sink to extend the water usage from one day to three days. This means that you use the greywater twice before releasing it in the environment. This lead to a dramatic reduction in square footage for collecting rainwater.
All in all the reduction was significant when you thought of some more advanced ways of collecting and using rainwater/greywater. By reusing water multiple times instead of creating a single use for them you have the ability to extend the amount of water that you do collect across multiple days without having to use a fresh supply. And by reducing the amount of fresh supply of rainwater, you can reduce the square footage dramatically.