Greywater-harvesting case study
Lancaster residence, 4 people, 2 goats, 6 chickens.
Tucson, Arizona, USA.
Elevation 2,555 feet (779 meters)
Average annual precipitation 11 inches (290 mm)…
• 1/8-acre property.
• See here for a One-Page Place Assessment of Tucson, Arizona
30 to 50% of the drinking water consumed by the average US single-family household is used to irrigate plants. That’s crazy! Think about all the resources consumed to treat our water to drinking water standards, then all the resources needed to install, maintain, and power a water distribution network that can export/deliver that drinking-/potable-quality water to every home and business. And then 30 to 50% of that drinking water is directed straight into the dirt to irrigate the household’s landscape and garden!
We don’t want to use/waste costly, imported drinking water for non-potable uses.
Instead, we want to harvest (NOT drain or throw away) and beneficially cycle and reinvest free on-site waters—especially for non-potable uses such as irrigation.
So, we set up all plantings within or beside water-harvesting earthworks so:
Free rainwater is the primary irrigation source
Free greywater is the secondary irrigation source
Municipal/well/drinking water is a supplementary source only used in true times of need.
A key strategy to making this work is we plant the rain before we plant any plant (multi-use native plants are the easiest to succeed with), then we also plant greywater before/where we plant any higher-water-use plant such as a non-native fruit tree.
See the plant appendix of Rainwater Harvesting for Drylands and Beyond, Volume 1, 3rd Edition for how to estimate the water needs of your plants, and see Volume 1 or 2 to estimate the volume of rainwater, greywater, and other free waters you have on site that could irrigate those plants.
All pipe distributing greywater maintains a minimum 2% downward slope to ensure free, effective gravity-fed distribution of the greywater.
See chapter 12 and Tool Box Level in appendix 1 of Rainwater Harvesting for Drylands and Beyond, Volume 2, 2nd Edition for more.
The average municipal/drinking water consumption per person per day in Tucson is 82 gallons, but thanks to our water-harvesting strategies our municipal/drinking water consumption is less than 20 gallons per person per day. And we have a verdant and productive landscape that, depending on the season can produce 10 to 25% of our households’ food needs.
Additionally, we are far more connected with where our water comes from, how much we use, how we use it, and how we can recycle it in myriad ways to improve the waters’ quality, help rehydrate our local watershed. These systems have also made us far more resilient in extreme weather by reducing the effects of drought in dry times and mitigating potential flooding in wet times.
For more information
on harvesting greywater and other free, on-site water sources see the following books available at deep discount direct from the author:
See the new, full-color, revised editions of Brad’s award-winning books
– available a deep discount, direct from Brad:
THE book to enable you to assess all your free on-site waters, then create an integrated water harvesting plan.
Includes the story of the transformation of the Lancaster residence.
Lots of step-by-step instructions on how to design, build, and plant many different kinds of rain and greywater gardens for many different contexts.
A whole chapter on greywater harvesting.
Case studies of how to change code to allow for safe, effective, and affordable greywater harvesting systems where you live.
An appendix on dark greywater harvesting.