Harvesting Rainwater

Eight Principles for Harvesting Rainwater from Brad Lancaster.

Brad Lancaster is a permaculture expert and consultant based in Tucson. His
award-winning book Rainwater
Harvesting for Drylands and Beyond, Volume I: Guiding Principles to Welcome Rain
into your Life and Landscape
(2006, Rainsource Press) and Rainwater
Harvesting for Drylands and Beyond, Volume 2: Water-Harvesting Earthworks

are available on the web at www.HarvestingRainwater.com and at
amazon.com.
This website also contains a bounty of free information, image, video, and audio
resources.

Lancaster Residence Food Production

Link: The Oil Drum | Abundant Skies: 8 Principles for Successful Rainwater Harvesting.

Principle #1: Begin with long and thoughtful observation.
Right after we bought the house, monsoon rains poured from the sky. Rodd and I got acquainted with where where runoff pooled against the house and how the bulk of the rain ran off our site into the street. We mapped these observations, and others, including noise, head¬lights, and pollution from the street; where we wanted privacy; where we needed shade; and where we needed to enhance winter solar exposure. Wherever you direct rainwater in your landscape, you will be nurturing plant life, so take the time to make ensure this vegetation is part of your overall plan.

Next, calculate the rainwater resources available within your site’s “watershed.” For us, that area included not only the 12 inches of annual rainfall on our roof and 1/8th of an acre property, but the 20 foot wide public right-of-way adjoining our property, the section of street draining past the right-of-way, and the runoff from our neighbor’s roof. (See Table, below) This totaled about 104,600 gallons (397,000 liters) of rainwater in an average year!

Principle #2: Start harvesting rain at the top of your watershed, then work your way down.
In most cases, the top of your watershed means the roof of your house.

Our leaky
asphalt roof was a mess, so we removed it and installed 26-gauge
galvanized steel metal roofing instead, which harvests rainwater in a
potable form. However, as long as you’re only harvesting rainwater for
use in landscape irrigation, this isn’t a necessary step. (Rainwater
harvested off a conventional asphalt roof can also be made safe for
consumption with the installation of an appropriate water filtration
system.)

Take a look at your roof. Where do the gutters drain? Where is
rainfall currently being directed? This is where you should begin with
mulched water-harvesting basins and plantings (at least 10 feet from
the building’s foundation.) On our property, just under half of the
roof runoff is directed to earthworks and fruit trees north of the
house. The rest is directed to an above-ground cistern west of the
garden along our property boundary on top of a 2-foot (60 cm) high
earthen platform.

Our cistern is a custom-modified new ferro-cement septic tank, but a
number of good alternatives exist. (See, Choosing a Tank.) We selected
the location of our cistern to provide multiple functions. By placing
it on the western boundary of our yard to shadeing out the hot
afternoon sun, it creates a beneficial microclimate for our garden. By
acting as part of the property line, it provides a privacy screen from
a peering neighbor. And by placing the cistern on an elevated platform,
the system utilizes gravity in circulating water from the roof’s gutter
to the tank, and from the tank to the garden.

Whatever type of cistern you choose, having your garden located
nearby will keep hose length to a minimum (25 ft. ideal) This will
reduce water-pressure loss to surface-friction inside the hose and make
watering with rainwater a convenience. (Your plants will love it too!)

Principle #3: Always plan an overflow route, and manage overflow as a resource.
Eventually, all water-harvesting systems will meet a storm that exceeds
their capacity, so don’t get taken by surprise. All rainwater
harvesting structures should be managed in such a way that the system
can overflow in a beneficial, rather than destructive way.

In that spirit, overflow from our backyard cistern is directed via a
4-inch diameter overflow pipe gutters to a series of adjoining mulched
basins that passively irrigate a citrus tree and our garden. In
addition, all of our sunken earthworks have an overflow “spillway.”
Typically, one earthwork overflows to another and another, until all
are full and then, if needed, the lowest earthwork can overflow to a
natural drainage–-or, in a typical urban context, the street.

Your goal should be to harvest the rain, but never get flooded by it. This is key.

4. Start with small and simple strategies that harvest the rain as close as possible to where it falls.
When people think of rainwater harvesting, usually it’s cisterns and
tanks that spring to mind. But the water collected off your roof is
typically much less than what’s actually falling on your property.
Simple water-harvesting earthworks, such as basins, terraces, contour
berms, and check dams will harvest the rain where it falls, on the land.

The water-harvesting earthworks Rodd and I created collect the vast
majority of our rain. We dug level-bottomed basins and deeply mulched
them (about 4 inches) in order to infiltrate rainfall and runoff
throughout our watershed—once again starting at the highest points of
the yard and working down. Overflow water was directed from the upper
basins to the lower basins, which brings us to principle number five.

5. Spread, slow and infiltrate the flow of water into the soil.
Cisterns along with mulched and vegetated earthworks basins with
overflow routes will effectively transform your erosive runoff during
heavy rainfall into a calm, productive resource while reducing water
loss to evaporation and downstream flooding.

Raised pathways and gathering areas are also a great strategy for
spreading water through the landscape. This pattern of “high and dry”
regions that drain to adjoining basins kept “sunken and moist” will
help to define those areas through vegetation while spreading and
sinking the flow of water. (This also helps keep ice off walkways and
driveways in colder regions.) At our place, we also used earthworks to
redirect the runoff that used to pool against our house to planting
areas 10 feet or more away from the building’s foundation.

6. Maximize living and organic groundcover.
All your basins and other water-harvesting earthworks should be well
mulched and planted. This creates a “living sponge” effect that will
utilize the harvested water to create food and beauty in your
surrounding landscape while steadily improving the soil’s ability to
infiltrate and hold water due to the vast network of growing roots and
beneficial micro-organisms.

Groundcover is equally important in helping to ensure that, in your
enthusiasm for harvesting rainwater, you don’t wind up creating a haven
for mosquitoes. Mosquitoes need three days of standing water to
transform from eggs to adults. Water-harvesting earthworks allowing
water to infiltrate below the surface of the soil (typically within one
hour) where it won’t be lost to evaporation.

Take a hike in the natural unmanaged areas near your home to
determine what native vegetation would be best to plant within or
beside your earthworks. Out in the wild, you’ll notice which plants
grow naturally in depressions – they can be planted within your basins.
Wild plants preferring better drainage can be planted beside, but not
within earthworks.

Blue palo verdes, velvet mesquite, chuparosa, oreganillo, and desert
lavender are a few of the native plants found along the ephemeral
washes in our area of Tucson that we plant within our earthworks.

7. Maximize beneficial relationships and efficiency by “stacking functions.”
As mentioned previously, water-harvesting strategies offer maximum
benefits when they’re integrated into a comprehensive overall siteplan.
We focused on locating the earthworks where we wanted to stack
functions with multi-use vegetation.

Through rainwater harvesting earthworks, we’ve nurtured a solar arc
of deciduous trees on the east, north, and west sides of our home that
cool us in the summer, but let in the free light and warmth of the sun
in winter. A living fence of native plants along the property line
(along with an existing citrus tree) form part of a sun trap. This
suntrap shades our garden from the afternoon sun, creates on-site
stormwater control, and enhances habitat for native songbirds and
butterflies.

The Big Picture
Within our generative landscape, rainwater has become our primary water
source, greywater our secondary water source, and municipal groundwater
a strictly and infrequently used supplemental source (meeting no more
than 5% of our exterior water needs). Most of our established landscape
has even become regenerative by thriving on rainwater alone.

Our household consumes less than 20,000 gallons of municipal water
annually, with over 90% of that being recycled in the landscape as
greywater. Additionally, we harvest and infiltrate over 100,000 gallons
of rain and runoff into the soil of our site (and, by extension, the
community’s watershed) over the course of our annual average rainfall.

As a household, we’re shifting more and more to living within our
rainwater “budget”: the natural limits of our local environment. As a
result, we’re enriching the land, growing up to 25% of our food on
site, creating a beautiful home and neighborhood environment – and
giving back more than we take!

The further we go, the easier and more fun it gets, which brings us to the eighth and last principle:

8.  Continually reassess your system and improve it.
Three years ago, Rodd and I set up an outdoor shower so the bather
could either use pressurized municipal water at the showerhead or
cistern water distributed from a shower bucket on a hook. Other
strategies have included a solar-powered greywater “laundromat” in our
backyard (utilized by seven neighboring households) along with a
reduction in impermeable hardscape by replacing our asphalt driveway
with lush plantings and earthworks.

One of our most rewarding recent improvements has been the process
of working with our neighbors and the city to replace 26% of the
pavement from the corner intersection with a water-harvesting traffic
circle planted with native vegetation. We also succeeded in
implementing a system that harvests street runoff within curbside
mulched basins to grow a greenbelt of trees along the street and
sidewalk, so the street now passively irrigates the trees.

As a result, our neighborhood—once the victim of urban blight—is now one of the greenest and most livable areas of the city.

My advice to anyone who wants to get started living more sustainably
is to start with rainwater-harvesting. Start at the top. Start small.
But above all—start!

Sidebar: Choosing a Rainwater Cistern
Our cistern has a 1,200-gallon (4,560 liter) capacity. We selected this
size after calculating the average annual roof runoff, assessing our
water needs, and determining the resources we wanted to commit to the
system. We opted for a precast concrete septic tank for a number of
reasons, but primarily because it was affordable as well as a workable
size and shape for our space (5 foot wide, 6 feet tall, 10 feet long).

Our septic tank was custom-made for use as a cistern, and further
reinforced for above-ground installation. The cost back in 1996 was
$600, which included delivery and placement. It’s been working great
ever since.

Other options for pre-manufactured cisterns include light-free dark
green or black polyurethane plastic, corrugated metal, and fiberglass.
See www.watertanks.com for options and look in the yellow pages under tanks for local suppliers.

Calculating Your Rainwater Resources
To calculate the volume of rain falling in an average year on a
specific surface such as your roof, yard, or neighborhood, use the
following calculation: CATCHMENT AREA (in square feet) multiplied by
the AVERAGE ANNUAL RAINFALL (in feet) multiplied by 7.48 (to convert
cubic feet to gallons) equals the TOTAL RAINWATER FALLING ON THAT
CATCHMENT IN AN AVERAGE YEAR: CATCHMENT AREA (ft2) x RAINFALL (ft) x
7.48 gal/ft3 = TOTAL AVAILABLE RAINWATER (gal/year).

Water in the American Desert

Barbara Kingsolver, in her book Animal, Vegetable, Miracle (page 4), wrote about living in Tucson, Arizona:

If it crosses your mind that water running through hundreds of miles of open ditch in a desert will evaporate and end up full of concentrated salts and muck, then let me tell you, that kind of negative thinking will never get you elected to public office in the state of Arizona. When this giant new tap turned on, developers drew up plans to roll pink stucco subdivisions across the desert in all directions. The rest of us were supposed to rejoice as the new flow rushed into our pipes, even as the city warned us that the water was kind of special. They said it was okay to drink, but don’t put it in an aquarium because it will kill the fish. She was describing life in Tucson, Arizona.

She and her family subsequently moved to a small farm in Virginia, where they started growing their own food and wrote a book about it.

The Carrying Capacity of the Land

We live in the Atlanta area, where August’s intense heat, with no rain, has turned into beautiful blue skies and low humidity in September through November, with almost no rain. The governor has blamed environmentalists for Atlanta’s main water source drying up and has started leading prayer groups to bring rain. It’s heresy to point out that the rapid residential and commercial development throughout the area has created an insatiable thirst for water that cannot be satisfied by the current water resources.

I’ve included some excerpts on the use of resources below from writer and thinker John Michael Greer. Ignore his message if you don’t use energy or water, or, if you believe that your favored political party will save us. One of the targets of his sharp writing tool is the drought in the Southeast and Atlanta. Click on the link below to enjoy the full flavor of his commentary of the current state of our culture.

Link: The Archdruid Report: Lifeboat Time

As depletion of existing oil fields accelerates, the struggle to prop up the current production plateau promises to become a losing battle against geological reality.

Meanwhile the carbon dioxide generated by the 84 million barrels a day we’re currently pumping and burning, along with equally unimaginable volumes of coal and natural gas, drives changes in climate that only a handful of oil company flacks and free-market fundamentalists still insist aren’t happening. Worried scientists report from Greenland and West Antarctica that for the first time since measurements began, liquid water is pooling under both these huge continental glaciers – the likely precursor to an ice sheet collapse that could put sea levels up 50 to 60 feet worldwide within our lifetimes.

In related news, Atlanta may just be on the verge of edging out New Orleans as the poster child for climate catastrophe. Unless the crippling years-long drought over the southeast United States gives way to heavy rains very soon, Atlanta will run completely out of drinking water sometime in the new year. The city government has had to explain to worried citizens that they are out of options, and there aren’t enough tanker trucks in all of Dixie to meet the daily water needs of a big city. Nobody is willing to talk about what will happen once the last muddy dregs in the Georgia reservoirs are pumped dry, and the drinking fountains, toilet tanks, and fire hydrants of greater metropolitan Atlanta have nothing to fill them but dust.

As Macchiavelli commented in a different context, though, people care more about their finances than their lives, and even the Atlanta papers have seen the drought shoved off the front page now and then by the latest round of implosions in the world of high finance. For those of my readers who haven’t been keeping score, banks and financial firms around the world spent most of the last decade handing out mortgages to anybody with a pulse, packaging up the right to profit from those mortgages into what may just be the most misnamed “securities” in the history of financial markets, and selling them to investors around the world.

On this noticeably unsteady foundation rose the biggest speculative bubble in recorded history, as would-be real estate moguls borrowed dizzying sums to buy up property they were convinced could only go up in value, while investors whose passion for profit blinded them to the risk of loss snapped up a torrent of exotic financial products whose connection to any significant source of value can be safely described as imaginary. All this hallucinated wealth, though, depended on the theory that people with no income, job, or assets could and would pay their mortgage bills on time, and when this didn’t happen, the whole tower of cards began coming apart. Some of the world’s largest banks have already taken billions of dollars in losses, and nobody is even pretending that the economic carnage is over yet.

Has Florida Mis-managed its water resources?

Unfettered real estate development has a price beyond the initial investment. Florida residents may be hit with very expensive water — soon.

Link: The Associated Press: Much of U.S. Could See a Water Shortage

Florida represents perhaps the nation’s greatest water irony. A hundred years ago, the state’s biggest problem was it had too much water. But decades of dikes, dams and water diversions have turned swamps into cities.

Little land is left to store water during wet seasons, and so much of the landscape has been paved over that water can no longer penetrate the ground in some places to recharge aquifers. As a result, the state is forced to flush millions of gallons of excess into the ocean to prevent flooding.

Also, the state dumps hundreds of billions of gallons a year of treated wastewater into the Atlantic through pipes — water that could otherwise be used for irrigation.

Florida’s environmental chief, Michael Sole, is seeking legislative action to get municipalities to reuse the wastewater.

"As these communities grow, instead of developing new water with new treatment systems, why not better manage the commodity they already have and produce an environmental benefit at the same time?" Sole said.

Florida leads the nation in water reuse by reclaiming some 240 billion gallons annually, but it is not nearly enough, Sole said.

"We just passed a crossroads. The chief water sources are basically gone," said John Mulliken, director of water supply for the South Florida Water Management District. "We really are at a critical moment in Florida history."

Rain and Drought

I am listening to the first hard rain we’ve had here since the end of July. It’s a wonderful sound.

For almost three months, every patch of rainy weather coming east across Alabama into Georgia has either not dropped rain or veered north or south of northern Georgia.

We depend on a well for our water. We are concerned — I’ve been taking short showers lately.

I hope our next home will have a plumbing system to provide gray water for the plants in the yard.

All of us in the United States are going to have to get smarter about water use. We can’t continue to use water (or energy) unwisely.

Beautiful Image: The Canadian Shield

The Shield by WB Skinner, who shot this photo near dark close to Thunder Bay, Ontario at a section of the Current River known simply as the Cascades.

Canadian Shield

WB Skinner writes:

The Canadian Shield, also known as the Precambrian Shield or Laurentian Plateau, covers about half of Canada as well as most of Greenland and part of the northern United States; an area of 4.4 million square kilometers (1.7 million square miles).

It is the oldest part of the North American crustal plate and contains fossils of bacteria and algae over 2 billion years old.

The shield is composed of granite and the earth’s greatest area of exposed Precambrian rock (igneous and metamorphic rock formed in the Precambrian geological era 500 million years ago).

The shield was the first part of the continent to be permanently raised above sea-level. Subsequent rising and falling, folding, erosion and continental ice sheets have created its present topography. The reoccurring invasion and withdrawal of the ice sheets (1.6 million to 10,000 years ago) depressed the surface creating Hudson Bay, scraped out tens of thousands of lake basins, carried away much of the soil cover and redeposited glacial debris.

via Dave Pollard

Ignorance Is Bliss — and Cancerous

The Atlanta Journal Constitution newspaper describes how the state of Georgia will spend settlement money from a company that dumped PCBs into a stream for 20 years.

Link: Lake Hartwell: Anglers’ paradise or peril? | ajc.com

The state [Georgia] plans to spend millions of dollars to make Lake Hartwell more fishing-friendly, but state officials won’t spend another dime telling anglers at the northeast Georgia reservoir that eating their catch could lead to cancer.

Toxic chemicals from a plant that once operated nearby still rest on the bottom of Lake Hartwell. They move up the food chain to the bass and catfish, posing a cancer risk to those who eat them on a regular basis.

Lake Hartwell’s changes will be funded by a $3.7 million settlement the state reached with Schlumberger Technology Corp., owner of the Pickens, S.C., manufacturing plant that for more than 20 years dumped carcinogenic polychlorinated biphenyls, or PCBs, into a stream that flowed into the lake.

The state plans to use the money to build boat ramps and fishing piers to entice even more visitors to Hartwell, already one of the most popular federal lakes in the country. Georgia also is spending other state funds to add more hybrid and striped bass to the lake — fatty-fleshed game fish that absorb and retain the most PCBs.

That might give anglers pause if they knew about it. But the state no longer posts warning signs around Lake Hartwell, although officials in neighboring South Carolina have signs on their side of the water.

Creative Thinking: The Play Pump

I saw a documentary on PBS Frontline about the Play Pump. Trevor Field, a true creative thinker, saw a problem (poor water quality and availability in South African villages) and designed a solution (a pump that taps an aquifer far underground and fills a holding tank above ground) powered by an untapped energy source (kids wanting to play.) Excerpts and video from Frontline below.

Link: FRONTLINE/WORLD . Rough Cut . South Africa: The Play Pump | PBS

Trevor Field, a retired advertising executive, had done well in life and wanted to give back to his community. He noticed that in many rural villages around the eastern Cape, the burden of collecting water fell mainly to the women and girls of the household. Each morning, he’d see them set off to the nearest borehole to collect water. They used leaky and often contaminated hand-pumps to collect the water, then they carried it back through the bush in buckets weighing 40 pounds. It was exhausting and time-consuming work.

"The amount of time these women are burning up collecting water, they could be at home looking after their kids, teaching their kids, being loving mothers." He knew there had to be a better solution.

Field then teamed up with an inventor and came up with the "play pump" — a children’s merry-go-round that pumps clean, safe drinking water from a deep borehole every time the children start to spin. Soup to nuts, the whole operation takes a few hours to install and costs around $7,000. Field’s idea proved so inventive, so cost-efficient and so much fun for the kids that World Bank recognized it as one of the best new grassroots ideas.

In true ad-man style, Field’s next idea was to use the play pump’s water towers as makeshift billboards, selling ad space to help pay for the upkeep. He reserves a spot for the national loveLife campaign, which helps educate children about HIV and AIDS. "We’ve got to get the message through to them before they become sexually active," he says. "It seems to be working."

In the film, Costello and producer/photographer Cassandra Herrman drive out to a small village where the taps have been dry for a week. There, a crew sets to work installing a play pump near a children’s play area, boring 40 meters down until they hit the fresh water table below. As soon as the last colorful piece of the puzzle is in place, dozens of children show up to play — much to Field’s delight — pumping cool, clean water to the surface as they spin.

The indefatigable entrepreneur wants to build thousands of these pumps to help water-stressed communities across South Africa, then expand to other African countries. He says, "It would make a major difference to the children, and that’s where our passion lies."

Watch the Frontline Play Pump video