The following principles are guidelines or reminders – like, did you consider this? They are flexible, not fixed. Because every design should be shaped by the specific conditions, potentials, and challenges of every unique site. They strive to lead you to more effective, integrated systems. Do not use these principles as a checklist whereby you just check off each principle if you’ve addressed it. Instead, use these principles to look for and see what you have not yet seen or addressed. For example, even if you used principle 2 and started at the top of your site in some way – look deeper. Could you do an even better job of this? Could your cistern overflow be out-letted at a higher point in the landscape? Used this way, they help you and your site to continue to evolve and develop, and you go further.
Feel free to evolve these principles or develop new ones as you learn from experience. My Volume 1 book expands on how these were developed and why.
Eight Principles of Successful Water Harvesting
Begin with long and thoughtful observation. Use all your senses to see where the water (and the sediment it carries) flows and how. What is working, what is not? Build on what works. Consider how you might help fix that which is not working.
Start at the top (highpoint) of your watershed and work your way down. Water travels downhill, so collect water at your high points for more immediate infiltration and easy gravity-fed distribution. Start at the top where it easier as there is less volume and velocity of water.
Start small and simple. Work at the human scale so you can build and repair everything. Many small strategies are far more effective than one big one when you are trying to infiltrate water into the soil.
Slow, spread, and infiltrate the flow of water. Rather than having water run erosively off the land’s surface, encourage it to stick around, hang out, and infiltrate into the soil. Slow it, spread it, sink it.
Always plan an overflow route, and manage that overflow as a resource. Always have an overflow route for the water in times of extra heavy rains, and where possible, use the overflow as a resource.
Maximize living and organic groundcover. Create a living sponge so the harvested water is used to grow more resources, while the soil’s ability to infiltrate and hold water steadily improves.
Maximize beneficial relationships and efficiency by “stacking functions.” Get your water harvesting strategies to do more than hold water. Berms can double as high-and-dry raised paths. Plantings can be placed to cool buildings in summer. Vegetation can be selected to provide food.
Continually reassess your system: the “feedback loop.” Observe how your work affects the site, beginning again with the first principle. Make any needed changes, using the principles to guide you.
Principles 2, 4, 5, and 6 are based on those developed and promoted by PELUM, the Participatory Ecological Land-Use Management association of east and southern Africa. Principles 1, 3, 7, and 8 are based on my own experiences and insights gained from other water harvesters.
These principles are the core of successful water harvesting. They apply equally to the conceptualization, design, and implementation of all water-harvesting landscapes. You must integrate all principles, not just your favorites, to realize a site’s full potential. Used together, these principles greatly enhance success, dramatically reduce mistakes, and enable you to adapt and integrate a range of strategies to meet site needs. While the principles remain constant, the strategies you use to achieve them will vary with each unique site.