One of the large goals that we have here at CommuniTree is to empower you as homeowners with the knowledge you need to successfully implement the same strategies we use during our design and installation processes. After giving a lecture at the Cuyamaca Water Conservation Gardens, I felt it would be useful to post some of the meat of the lecture here. Since a large basis of the class was centered around Brad Lancaster's teachings, here it is: The 8 Principles of Successful Water Harvesting!
1. Begin With Long and Thoughtful Observation
Use all of your senses to see where the water flows and how. What's working? What's not? Build on what's working. How much water can be harvested? Where are your access points? What does the natural grade of the landscape look like? What are the planting possibilities?
2. Start at the Top (Highpoint) of Your Watershed and Work Down
Water travels downhill so collect water at high points for more immediate infiltration and easy gravity fed distribution. Start at the top where there is less volume and velocity of water. For your home this will most likely be your roof!
3. Start Small and Simple
Work at the human scale so you can build and repair everything yourself. Many small strategies are far more effective than one big strategy when trying to infiltrate water into the soil. Like I said earlier, the idea is that you can do this work yourself!
4. Slow, Spread, and Sink
This is the meat of this list if you ask me. Rather than have water run erosively off the land's surface, encourage it to stick around, "walk" around, and infiltrate it into the soil. Think of places that you see fast moving water. Coastal cliffs, down our roofs, and down our streets are all opportunities to slow water down and get it into the most inexpensive rain tank of all....the soil!
There are several tools that can be used for this based on the specific job. Swales and berms are good for hills while infiltration basins are more useful for flat areas. The idea for both is to catch water in depressions in the earth allowing one to plant up around them. These depressions are filled with mulch or other organic material to create a sponge for holding more water.
5. Maximize Living and Organic Groundcover
Create a living sponge so the harvested rainwater is used to create more resources while the soil's ability to infiltrate and hold water steadily improves. This will shade your soil, fight evaporation, and improve the quality of your soil below by assuring the presence of good bacteria and fungi. See lectures from Elaine Ingham for further exploration into soil health.
6. Always Plan an Overflow Route and Manage Your Overflow as a Resource
Have an overflow route in times of heavy rains and where possible use this overflow to benefit your space. Direct the extra water to basins and plantings that are in need of more water.
7. Stack Functions
Get your water harvesting strategies to do more than just hold water. Berms can double as high and dry raised paths, plantings can cool buildings, and vegetation can provide food. Plant guilds are an example of stacking functions. One can flush salts from greywater setups with rainwater overflow. The big idea here being to achieve as much as possible with little system disruption and effort.
8. The Feedback Loop
Continuously reassess the system that you have created. Observe how your work affects the site, beginning again with the first principle. Make any needed changes using the principles to guide you.
There you have it, a lot of common sense, a bit of ingenuity, and constant reassessment. Remember all of these steps work together and are equally important and as Brad says, "used together these principles enhance success, dramatically reduce mistakes, and enable you to adapt and integrate a range of strategies to meet site needs."