A keystone element of sustainability is water conservation and, for a desert garden, rainwater collection is paramount. The DOT Garden in collaboration with Adaptive Terrain Systems (a Division of Soilutions), New Mexico Water Collaborative, and the ABC Water Utility Authority designed and installed 3 systems for rainwater harvesting and use.
So how do you begin a rainwater harvesting project?
With lots of questions, planning, and ideas. Research, reading the work of Brad Lancaster, online videos, and the guidance of local experts are all really helpful too. It helps to answer some basics like: How big is the roof? How much water can I use? Is there an overflow plan? Is the water for plants, animals or people? How does this catchment fit in with the big picture for the space now and in the future?
Really great news for all of us!
The New Mexico Water Collaborative is updating a rainwater collection guide for our region. It will have loads of information, installation stories and plans from right here in Albuquerque, plus links to installers, gutter companies, and more. The complete DOTG cistern project will be included here. The Guide should be available spring 2016 in print form and online. Keep checking here FMI: http://nmwatercollaborative.org/projects/rainwater-harvesting-project/
DOTG cistern installation project overview
We installed three rainwater collection systems: cistern #1 in May in the courtyard, and cisterns #2 & #3 in August near our raised bed area. Taking advantage of summer monsoons, we used rain catchment from #1 to irrigate vegetables, supply water for our greenhouse starts, brew compost tea, and supplement a small pond that is home to fish, frogs, and a water source for birds and insects. Cisterns #2 & #3 are serving our major food production area, which includes 9 raised beds and 4 sunken beds devoted to the cultivation of vegetable and grain crops, as well as 10 mature pine trees, and a cover cropped Meadow.
Some cool design features and photos
Cisterns are 1,650 gallons each, about 5’8” tall, 24’ around, and made of heavy duty black cross-linked polyethylene that has been proved to be algae and mold resistant. (Sourced from Phil Monfette, www.ineedawatertank.com )
We used inexpensive crusher fine, packed down as a substrate and a level pad for the cisterns. (Sourced from Vulcan Materials Company, www.vulcanmaterials.com )
To exclude sunlight from making algae and bacteria grow inside the cisterns:
For cistern #1, we updated an existing system which did not have vertical clearance for a bend in the downflow to reduce/eliminate sun from entering the cistern. We had to make an “internal downspout shade” – a small angled piece of metal was screwed into the downspout.
For cisterns #2 and #3: Simple elbow-bend in downspout so sunlight cannot enter from above.
(All our guttering repairs and new installations were done by ABQ Gutter Pros, Inc., David Palsce, 505-345-1640.)
Bulkhead fittings on Cistern #1 are really durable and tight fitting. From Banjo brand valves and fittings( http://www.banjovalves.com )
Frost-free spigot for gravity outflow at base: Designed by Jim Brooks, this experimental design uses a vacuum breaker, extra long internal pipe, and is tilted toward the outside to prevent freezing. This should allow us to keep water in the cisterns over the winter so that rainwater is available for early spring planting. We may even be able to use it all winter in our row-covered beds. We’ll keep you posted.
Utility-pump assisted outflow from the bulkhead near the top: A standard utility pump is lowered into the tank, rests on the bottom of tank with the pump hose quick-connected to the junction in the vertical hatch area, then standard garden hose is connected for a low-flow pumping outflow. We’ve even got electrical cord dry-connection options on Cisterns #2 and #3 if we want to keep the pumps in longer term.
Custom-designed easy-to-lift downspout connection to the cistern inflow. We needed a connection that was easy to move by kids and adults and we got it! This way we can check easily clean the filter basket, look for biological growth (that we don’t want), and access the pump outflow quick-connect.
Our OverFlow Plans are fantastic! The internal system is a bit complex but basically allows rainwater inside the cistern to run into internal ABS pipes near the top and then water comes out near the bottom.
The surge basins, swales and sponges were designed by Tiana Baca, our Garden Manager and permaculturist, with guidance from Adaptive Terrain Systems. All these systems are working really well.
Special thanks to the Project Learning Tree Greenworks and William H. and Mattie Wattis Harris for funding this project, Whole Foods Academy for lunches, Jim Brooks and his crews, the participants in our August installation, and all our community volunteers. We got RAINWATER!