Sustainable Design as it relates to water has some principles that are universal to all good design.

These include:
1. Repeatable over long periods of time with minimal input or ecological damage.
2. Natural Mimicry to create diversity and resiliency. This leads to systems that are mechanically simple and biologically complex as the preferred models.
3. In general, Simpler is Better and, Easier to Copy.

There are also principles that are unique to Moisture management .

1. Slow the flow of moisture through a watershed, community, or landscape. All water systems on earth have the same basic elements. These are sourcing, consumption, and return flows. Sourcing refers to where the water comes from. Consumption is the water that is “used up” and returns to the sky by evaporation. Return flows are used in the system and then exit to a point downhill usually in a sewer pipe. The are a number of ways to slow moisture flows. The first efforts are taken aty the top pf the watershed to assure that water infiltrates and is held as high up in the landscape as possible. Where water is stored in a reservoir, the best place is higher altitudes with less potential for evaporation. In the built environment, we seek to create sponges. There are areas of permeable surface and soil where water can be infiltrated for later withdrawal by plants or mechanical systems. In our communities and farms, we design for the highest efficiency of water in to benefits out. This ranges from drip irrigation to low flow shower heads that still provide a comfortable and refreshing shower. We also seek to reuse water whenever possible as many times as possible.
2. Design Budgets For Water, Energy, and Money. Water is brought into the system in pipes, but the real sources are from surface water, ground water, or precipitation that is harvested on site. Because of the convenience of plumbing systems, the use of precipitation as a source has been neglected. There are specific calculations that predict the amount of precipitation that can be passively harvested in soils, actively harvested in tanks and cisterns, and in some cases the amount that must be allowed to flow from the community for downstream users. These calculations are generally presented in the form of a water budget. Water budgets have summaries of supply, demand and reserves, and they can be created on different scales from household to regional level. Usually, the movement or treatment of water involves the use of energy. Most energy is produced as electric current and water is consumed in the process. A recent study of coal fired power plants in Northwest New Mexico showed a consumption of .75 gallons (2.84 liters) per kilowatt hour of electricity production.
3. Match Quality to Purpose Sustainable water management seeks to balance supply and demand while matching quality to use. A perfect example of this is the reuse of greywater or treated blackwater for flushing toilets or irrigating landscapes. This saves the water, money, and energy that would have been used to capture the water, treat the water, deliver the water, collect the sewage, treat the sewage, and release the effluent. Instead water is reused on site at a quality level appropriate for its purpose. In plain language, flushing a toilet with drinking water is not very smart.

Content © 2007 Earthwrights