Eight Principles for Successful Rainwater Harvesting

The following is a guest post by Brad Lancaster on rainwater harvesting, that I posted about a year ago. Energy scarcity and water scarcity are closely related phenomena, especially in certain parts of the world. While rainwater harvesting is no panacea for our water or energy problems, it may be a critical component in many regions for dealing with issues of scarcity. It is also an excellent example of a scale-free tool: it can be implemented by individuals, communities, or nations.

Food produced from rainwater on Brad Lancaster's Tucson residence

Brad Lancasteris 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.

My interest in water -harvesting arose from a desire both to reduce my cost of living and to be part of the solution rather than the problem in my desert city of Tucson, Arizona. One of Tucson’s biggest problems is its mismanagement of water resources, pulling more each year from the water table than nature can replace. This is a practice that has dried out the Santa Cruz river, killed countless springs and wells, and severely depleted available groundwater resources.

Living in the desert has put a special emphasis on water -harvesting for me, but it’s a valuable strategy for non-desert environments, too. Rainwater harvesting is effective for reducing or preventing erosion and downstream flooding while improving stormwater quality. Thus, Portland and Seattle have embraced water-harvesting to protect salmon populations, and Maryland is doing the same to protect the Chesapeake Bay. And anywhere in the world, water -harvesting is a smart strategy for helping to recharge groundwater tables, springs, wells, and rivers.

Back in 1994, my brother Rodd was also interested in water-harvesting, but as long as we were both renting, all we could do was read up on the subject. At the time, we were both self-employed, making what the government considers poverty wages. No bank would touch us. On our own, neither of us could afford to purchase a home, but together, it was feasible. (It helped that the house we wound up purchasing was about to be condemned.) We did 95% of the renovation work ourselves and used mainly salvaged materials.

Twelve years later, our property value has shot through the roof. The integrated water-harvesting techniques Rodd and I learned and implemented on this once-barren urban lot have transformed it into an oasis in the desert, with temperatures ranging an average ten degrees lower than our neighbors’. Our land produces 15-25% of our food, which includes organic, homegrown fruits, nuts, vegetables, eggs, honey, and mesquite flour grown solely with rainwater and greywater (reclaimed household wash-water.) Our utility bills have been dropping steadily since we moved in and now run an average $20 per month.

The Lancaster residence before renovation in 1994

2006, after renovation: rainwater and greywater utilized for food production, climate control, privacy.

In the course of creating our sustainable oasis here in Tucson, Rodd and I arrived at eight basic principles that anyone can use to implement a successful rainwater-harvesting strategy of their own.

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!

Enjoying a shady right-of-way produced by rainwater-irrigated, food-producing trees at the Lancaster residence

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)

A couple of update comments:

First, a related legal update, Colorado, once home to the most restrictive rainwater harvesting laws in the country, has significantly relaxed the rules.

Thanks for post. It’s really imformative stuff.
I really like to read.Hope to learn a lot and have a nice experience here! my best regards guys!

Update comment #2:

While there are many direct connections between rainwater harvesting and peak oil (such as the energy used in most municipal water supplies, the need for water to grow food if it can’t be trucked in, etc.), there is a subtler point that Brad’s article demonstrates brilliantly by way of example: there is very profound value to be found in decentralization per se. In terms of resiliency, quality of life, civil society, and political structure, look at what happens when individuals become self-sufficient in terms of water. Now imagine that spreading to water, food, and energy…

Update comment #3:

Brad’s rainwater harvesting post is also an important example of a trend that I expect will become increasingly important in a world where declining energy surpluses can no longer support the same scope and scale of centralized structures: a growth in open-source technology and vernacular/localized production. The kind of techniques that Brad outlines can 1) be easily adapted to locations and circumstances in an open-source manner, and 2) can just as easily apply to personal fabrication, food production, energy production, etc.

harvesting rainwater and growing some food can be personally satisfying but unless water is supplied by pumping deep aquifers or transported very long distances only a minimal amount of energy is used in supplying water. Many cities have gravity fed distribution. Food production and transportation only uses 3.3% of US energy consumption.
The big energy users are homes and commercial buildings( heat, A/C and light) and cars and light trucks. These two together use about 20 times as much energy as food production and water distribution combined.

Agreed--the delivery of water itself is relatively low energy-use, and from an residential energy conservation perspective we should righly focus on things like lighting, heating, cooling, etc.

However, our current water supplies are predicated on a long list of assumptions and tend to be "cascading failure" systems:

- We assume that the vast network of pipes, collection, storage, and treatment facilities that exist to deliver water to our houses will continue to operate normally, without attack, political disruption, failure of funding or energy of maintenance providers, etc.
- In the longer term, we assume that we'll have the energy required to maintain or re-build dams, dredge reservoirs, produce the metals and cement used in most transportation and distribution systems, etc.
- We (not meaning "you" specifically, but society in general) likewise assume that we'll be able to continue to get food at the market that has been trucked in from 1000 miles away, stored in refrigerated cases, and produced using fossil-fuel intensive fertilizers and equipment.

Rainwater harvesting and personal storage, combined with individual food production, can eliminate, or at last buffer, these long chains of dependencies--all of which are vulnerable to one degree or another due to peak oil.

I AM impressed.

And I suspect that if you could get your nieghbors to undertake such efforts,you would find it very well worth your while to sell out and move someplace where the rain gods are not so stingy!

As a practical matter if I lived in such a place,with my life long friends and relatives nearby,I would try to ride by and make your acquaintance,and get busy following your example.

But I reccomend that anyone contemplating a move consider only places with much better average rainfall.

You already have more people living in your neck of the woods than the local water supply can support if there is any loss of rain due to climate change,or even a plain old four or five year drought,most likely.

You already have more people living in your neck of the woods than the local water supply can support...

Far more, by several orders of magnitude. The only way this overpopulation is supported is by the Central Arizona Project taking massive amounts of Colorado River watershed runoff and transporting it in a series of huge canals to these population centers in the Sonoran Desert. It is the height of human folly and hubris and is absolutely unsustainable in the fossil fuel depleted near future. Millions of people are going to have to relocate or die. That's all there is to it.

Once when younger I was working on a thinning contract in the Apache-Sitgreves National Forest. The contract specs required that slash be stacked in the drains to be burnt later. I questioned the Forest Service COR about this: "Wouldn't it be better to leave the slash in the drains to retard runoff and promote inflitration?" I asked. His response was to the effect that the CAP owned rights to that water and they didn't want it infiltrating to the benefit of the forest. They wanted it to run off to fill the canals to the benefit of the hordes of the desert megalopolises. To fill their swimming pools and evaporative coolers. That's how crazy & ridiculous the situation is.

**to clarify, I live in Colorado--this post was written by Brad Lancaster, and it features his property in Tucson.

I agree that there are more people living in Arizona than can be fed by historical gathering techniques or by modern industrial agriculture without outside energy and water input. I disagree, however, that there are more people than can be supported sustainably. While population reduction would certainly assist in sustainbility, I think there is plenty of potential to support the present population of Arizona (even Phoenix) using new methods that mix old and new (much like Brad is showing at his property).

Simple numbers: Arizona has about 73 million acres of land, and a population of about 6.5 million--that's about 11 acres per person. Even assuming you use only 10% of that land, that's over one acre per person. Planting those acres with mesquite (and associated, food producing plant guilds) with application of some simple rainwater harvesting (similar to what you see in the photos above) would yield far more calories--even in extreme drought years--than would be necessary to support that population. Is that a ridiculous proposal? Perhaps, but my point is that it is *theoretically possible* for Arizona to support itself with food using only rainwater. The limiting factor is what is politically and culturally viable, and there I fear the Southwest will be in for some very tough times...

The broader point--and why I think this is an article of general applicability--is that considerations of what is *possible* at the extremes of the envelope are very useful for people more squarely in the middle of that envelope...

I'm sorry Jeff, I mean no disrespect but when I see you living off the production of one acre of mesquite watered only with the precipitation that falls on that acre, then I will afford your assertions some credibility. I'm all for rainwater harvesting in arid & semiarid regions - even tho it's likely illegal under Western water law - but it is useful only for landscape and perhaps limited horticultural irrigation supplementation. The idea that anywhere near the current population of the desert Southwest could possibly sustain itself in such a way truly is a "ridiculous proposal."

Fair enough. I'll admit that it may be unlikely, but I'd certainly like to see someone try it--in my mind, this would be a worthwhile project for an agricultural research grant or ag extension office, if for no other reason than to establish that we truly don't know how to make this happen even with best efforts... while I share your sentiment that the population of Arizona is probably 10x an easily sustainable level, I'm not ready to write it off. At a minimum, I'm not sure it's any less realistic than, say, New York state supporting itself at current population levels and no outside inputs--just a different set of limiting factors to deal with.

Living off the mesquite,etc, is one thing as far as a basic food supply goes but it's another altogether to find enough water to actually drink, bathe,keep a cow or a horse, put out a fire,or irrigate a few tomatos and cucumbers to go with your mesquite beans.

Would you care to hazard a guess as to what portion of the state is within say a half a mile of a year round stream of drinkable water? Or located over a substantial aquifer that is within a few hunderd feet of the surface?

If the Colorado ever fails you ,these are do or die questions for any individuals expecting to remain in the area.

"I'd certainly like to see someone try it (Growing your total diet)--in my mind, this would be a worthwhile project for an agricultural research grant or ag extension office, if for no other reason than to establish that we truly don't know how to make this happen even with best efforts.... "

I'll try ...

I did it before and if someone wants to give me some grant money that would be okay also.

How many calories did the parcel in Arizona produce ?

How much arable land was involved ?

I think it was Oldfarmermac who suggested it would take 2.5A per adult.

So, on 2.5 acres you would grow/eat what ??

I'm duplicating a comment from below, with additional thoughts to follow:

Some quick mesquite math: Mesquite flour is 2060 calories (based on conversion from commercially available mesquite flour). According to at least one Purdue University report, you can harvest 4,000 lbs per acre, per year in the semi-arid southwest. That works out to 8.24 million calories per year per acre, or 22,575 calories per day per acre (mesquite stores well, so seasonality of harvest isn't a major hurdle).

What remains unknown is what % of calories from mesquite is tolerable (it's unhealthy and very challenging, for example, to get 2,000 calories a day from just potatoes). Either way, a high quality of life would want a significant amount of nutrition and flavor from other food crops. That said, 1/10th of an acre seems to be the minimum to provide just enough calories from mesquite for one person. In reality, including rainwater catchment areas, other food crops, and building in significant surplus for bad drought years or poor harvest, it doesn't seem impossible to suggest that, in the arid Southwest, it is possible to reliably support 1 person per acre from rainfall alone.

So, the demonstration plot challenge that I'd like to see attempted is this: produce, from a mesquite-centered food forest, a tasty and balanced diet for 4 adults on 1 acre using only rainfall (I'd like to see this tried in Tucson and Phoenix to determine if it's possible in those two main population centers) and no outside inputs after establishment, and chronicle the yield over at least 10 years to demonstrate the effect of drought, etc. The bar must be met within 5 years after planting from a bare lot (to provide an example that could meaningfully scale). I'll admit that's a high bar, but I think it might be done. Maybe an arid-lands X-prize--anyone have a spare $10 million?? It sure seems like a better use of government funds than much of the current US budget, even if it fails, and seems like at least as worthy an outlet for human creativity as a manned mission to mars, etc... give grants to establish and maintain 10 plots for the 5 year period, with a prize to the best performer that meets the requirements.

How about a " tasty and balanced diet for 4 adults on 1 acre " ? to start with

using any plant materials... ??

If the natives grew corn , beans , squash etc. why not try that ?

4 people x 2000 calories = 8000 calories every day off 1 acre

they get up each day and eat what ??

Fats , proteins and carbohydrates ... from ??

a serving of mesquite flower is 68 calories ... 1932 calories left to go

what else is consumed in a regular day


I said 2.5 acres to be reasonably sure of long term survival per person if things go wrong-this provides a SUBSTANTIAL SAFETY CUSHION,which I feel is reasonable for someone planning for life after the big crash,if it comes,in an area similar to the one where I live.It also allows for what I see as a tolerably liveable lifestyle in terms of a varied diet,etc,as opposed to just having enough to eat.

If you think you can get food shipped in in case of a crop failure,and you think you will be able to pay for it,you could get by with much less land per person.Even as little as half an acre might suffice-until things start going wrong!

Things always go wrong.Sooner or later.

I feel it will take the 2.5A even in good conditions.

.5 Acres ? of what??

Grain , Legumes , Animals, oil crops, greens, roots ??

2000 calories every day ? at least 2 acres/person

There is a possible problem in that you want soft permeable soils to grow plants but between those areas you want compacted zones to direct runoff. A bigger issue is whether cities have grown too large for their piped water supplies. Perhaps some cities should shrink in population to remain within their sustainable water supply. However I guess nobody really wants to move from sunny to rainy areas.

I agree with filtering tank water. I put waterproofing compound on my roof and the tank water tasted weird until I installed an inline charcoal filter. I would guess you still needed piped water. If two adults each need 150 litres of water a day then 4500/300 = 15 days supply. I would go for a tank of 50 kL or 13,000 US gallons. Storms should gradually fill it and you would have 6 months supply if rain or piped water stopped suddenly.

I think that an interesting take-away from Brad's post is that you don't necessarily have to "move from sunny to rainy areas." Tucson (12" rain/year) is way toward the dry/sunny side of the spectrum, yet there is a great deal of potential. For the permeability/packed issue, most of existing suburbia has enough roof-space and hardscaping per person to provide a fair amount of rainwater harvesting for plants, and the use of swales and rainwater basins can fill the gap, with a nice balance between loose, arable soil and surfaces that generate run-off.

so .... given this parcel ..... How many adults could it sustain ?

what is the daily diet ?

Good questions... I think the theoretical daily diet (in Tucson) would be much like the top photo. And I think his lot is around 1/5th acre, but I have no idea how many calories. I can't find the reference at the moment, but I believe mesquite alone (native, requires only rainfall) produces enough calories on 1/5th acre to feed about 3 people a high protein diet. My guess is that his garden produces less than this, though...

How many mesquite beans would 1 person eat in a day ?


What % of the 2000 calories would that represent ?

How many mesquite beans do you get from 1 tree ?

Some quick mesquite math: Mesquite flour is 2060 calories (based on conversion from commercially available mesquite flour). According to at least one Purdue University report, you can harvest 4,000 lbs per acre, per year in the semi-arid southwest. That works out to 8.24 million calories per year per acre, or 22,575 calories per day per acre (mesquite stores well, so seasonality of harvest isn't a major hurdle).

What remains unknown is what % of calories from mesquite is tolerable (it's unhealthy and very challenging, for example, to get 2,000 calories a day from just potatoes). Either way, a high quality of life would want a significant amount of nutrition and flavor from other food crops. That said, 1/10th of an acre seems to be the minimum to provide just enough calories from mesquite for one person. In reality, including rainwater catchment areas, other food crops, and building in significant surplus for bad drought years or poor harvest, it doesn't seem impossible to suggest that, in the arid Southwest, it is possible to reliably support 1 person per acre from rainfall alone.

I don't exactly do rain water harvesting but the runoff water from our roof is directed to an old, shallow (150') well that I hope eventually perks down to the water table (417' - the pump is set at 450') where our current well is located. I guess I've had this set-up in place for 20 years or so.

FWIW, we get between 60-80 inches during the winter rainy season in northern CA.


so ... its ground water ,

rainwater catchment ,

or flowing water (snow pack and rain).

ground water requires a pump,

I think Todd once said ....move to where there is flowing clean water

Not many places left like that in a good growing area with class 1-3 soils.

So maybe a catchment system and pumping ... hand or solar ???

900 sq ft of rain catchment and a solar pump ...

how much food could I grow with min. FF ?


We have found the best way to save water is through low pressure gravity systems. When living in town we (2 people, but includes visiting children etc.) used 200,000 litres per year and now out in the bush, relying soley on rainwater, we use around 30,000 or so litres in the house,

Our grey water system is a worm digester sewage system from www.wormfarm.com.au, and so we have closed the nuitrient cycle as well.

We store around 40,000 litres for the house, and a lot more for the garden - mainly in an earth dam of over a million litres, from which we occasionally draw from in summer.

I feel a galvanised iron roof to be essential, while the best storage is in concrete tanks, we use food grade poly tanks from http://www.polyworld.com.au/rainwater.htm; which draw from a shed up hill a little from the house. The house water is collected and used for the garden.

I was wondering if the vegetation in the picture needs a fair amount of fertilizer to keep producing. Perhaps if Brad stops by. It seems like one would need both water and fertilizer to maintain such a lush landscape.

I'm not the expert, but I did live in Tucson for two years and noticed that the native flora (such as mesquite and palo verde) stay very lush without any outside fertilizer (though they both do better with some supplemental water--they survive on the average 12" a year, but really flourish if they have a rainwater collecting basin that gives them effectively 1.5x to 2x that amount. The key for trees (pictured in the bottom photo) like mesquite and palo verde is that they are naturally nitrogen-fixing (like beans), and therefore produce much of their own nutrient requirement without added fertilizer. This also makes them excellent for providing nutrients to other plants in the garden if used correctly.

The mesquite really is an amazing plant: it produces a very high-protein seed pod that can be used to make a flour, syrup, or beer; it produces a very high level of calories per square foot; it survives well on the average rain in most arid areas; it produces excellent hardwood and charcoal; it has dozens of medicinal uses; and it can be very beautiful, just to name a few attributes...

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)

A gallon is 231.0 cubic inches. For some reason 231 in3/gal sticks in my head better than 7.48 gal/ft3. The alternative formula: CATCHMENT AREA (in2) * RAINFALL (in) / 231 = gal

900 sq ft of roof x 1.83'(22" annual rainfall)/year x 7.48 = 12,320 gal/year

Collected in the winter -spring ...

going into the dry summer (no rain) , I could hope for maybe 9000 gal ?? to get threw till the first fall/winter rain.

tanks cost about $1/gal = $9000

Or spend $9000 on a solar pump and well ??

I just bit the bullet yesterday and contracted to have a hand pump installed on our deep well (180 ft deep, static water level at 90 ft). Our farm is 100+ years old, rainfed agriculture. The farm animals had the well water and the wells are located at the barn. The farmhouse had (still has, but not functioning) as cistern-- a huge cistern like 18X22X22 ft.

I think what's important about this post is to reclaim past knowledge and practices for household/farmscale water systems. We need more of this knowledge for hard winter areas like ours. I seriously wonder at the amount of work that is needed to keep ice free water for livestock in winters that can be below zero for days/weeks on end.

Brad Lancaster's Tucson residence seems to be a great idea.
Keep it up!

The Hohokam were experts in rainwater harvesting & dryland agriculture in general. Their civilization collapsed under a much lower population pressure than today's. The bigger the population the harder it falls.

Where I live the average annual precip is 8.2" Last year we only received 6.3" and it looks like this year will be below the mean likewise. I don't own water rights to the precip that falls, nor to the water in the river (glorified arroyo is more like it) that crosses my property. I do, however, own rights to water in an acequia that heads on a different, larger river. I take all the water I can and grow food & fuelwood with it. The irrigation infrastructure collapses or the snowpack diminishes significantly and I must move to where it rains or die. Two of my three children live in the Phoenix region and I fear for their lives when TSHTF.

While I think that our understanding of precisely why the Hohokam civilization collapsed is far from perfect, there's general consensus that it was largely similar to the events that led to the collapse of the related Chacoan civilization: the centralized and hierarchal structure of the civilization--really a regional redistribution network that moderated regional droughts--became top-heavy and rigid and then collapsed under some kind of climate stress. We don't know that people starved as a result, but rather that the superstructure that left behind significant archeological evidence could no longer be supported--quite likely the population simply shifted in mode to become the precursors to the Tohono O'odham and other area peoples. See this post for an interesting parallel.

Anyway, none of that is to suggest that there won't be serious problems in places like Phoenix for those unprepared. With enough advance planning and a shift from centralized/high-energy infrastructure to decentralized/low-energy infrastructure (like personal rainwater harvesting), I think that even the Phoenix area (arguably THE example of energy-fueled unsustainability) could become sustainable in terms of food, water, heating, cooling, etc. What worries me more is that people will choose not to take this path based on promises that they'll be able to return to business as usual, and will get sucked into exactly the kind of increasingly stratified social structure that we saw when the Chacoans (presumably) chose to accept the rule of a priestly class of redistributors in exchange for (ultimately illusory) security of food and water.

What happened to the Chacoan & Mesa Verdean "Anasazi" (I hate to use that term as it is racist: aana'i' = "enemy," sani' = "old" or "ancient") is that they were heavily impacted by invading Na Dene speaking peoples. The shift from dwelling in pithouses near agricultural tracts to defensible positions remote from their fields is evidence of this. It's not clear that the Hohokam at lower elevation further south where evapotranspiration is greater were as impacted as much by these subarctic big game hunting cultures that happened to wander south. It's more likely that developing interpluvial conditions following the last glaciation resulted in warmer & drier conditions that irrigation infrastructure construction & maintenance could not keep pace with in the face of growing population pressure. The Hohokam were the ancestors of the Tohono O'odham. When irrigated agriculture could not be maintained population collapse ensued and the survivors took to foraging the desert which proved a very successful strategy so long as population density remained low. As you probably know, these people today suffer inordinately from obesity, type 2 diabetes and alcoholism under a Westernized diet and lifestyle.

The only sustainable way to survive in the Sonoran Desert sans fossil fuels is to forage like the Tohono O'odham used to do. The population density today is orders of magnitude too high for this strategy to be employed by all but a handful of people. Also, the extensive and intensive knowledge required for successful foraging is all but lost, even by the Tohono O'odham and other aboriginal peoples themselves. The bottom line is that the vast majority of people had better get out of the arid Southwest while the getting is still good.

The Hohokam created the largest irrigation systems in the prehistoric New World.


the early Hohokam excavated long and complex canal systems to irrigate their fields of corn, beans, squash and other crops. They dug wells to tap underground water sources.


If ever in Phoenix , go to the museums.

great article Jeff ... thanks

The sophistication of Hohokam irrigation infrastructure rivaled that of China and Egypt of its time. This infrastructure allowed population in the lower Salt & middle Gila drainages to reach as high as 50K during the 12th century. Then, between 1350 & 1375, Hohokam culture abruptly collapsed. Population was reduced to a meager remnant who foraged the desert and no longer built large structures including irrigation canals. The current population of Phoenix is 1.5 million and that of Tucson .8 million. If the Hohokam exhausted the resource base of the region with a population of a mere 50K, back when the carrying capacity was higher than it is today, what's going to happen when fossil fuel depletion makes the Central Arizona Project inviable? This should be the message, and no amount of rainwater harvesting is going to prevent the inevitable.

If one lives in an area where the temperature goes below freezing for any length of time, you need to plan your entire system so you can drain out ALL the water before it freezes and breaks all your pipes and storage containers.

Nice posting.
We recently acquired, for $50, a 250 gallon tank (IBC - Intermediate Bulk Container Totes) much like this: http://www.interstateproducts.com/images/containment/ibcplus-clipboard.jpg Runoff from ours goes thru the raspberry bed, upper garden, fruit trees into the lower raspberry bed.

It must be because of that water tank that we've had a very wet season with a lack of heat. We keep watching this thing overflow ....

I've never had luck with drip irrigation yet (too much of a pain to turn the ground, bury the pipes, then dig them up after the growing season - but it would seem to be important.

I'd suggest reading The Humanure Handbook http://www.jenkinspublishing.com/humanure.html and seeing if you can find http://www.liquidgoldbook.com/
You want to recycle nutrients as much as possible - not just throw them away. So much is wasted down the drain.

In my part of the world I refused to pave the driveway - but in the end the developer came back and paved the first 2 yards (owned by the city) because my interlocking stone driveway (just 2 strips of stone where the wheeltracks go) was not considered "stable".

Many people could dramatically reduce their water use (toilet, unnecessary things like washing vehicles and clothes too much). We recently were part of the Yellow Fish Road project in the area http://www.yellowfishroad.org/ and had almost hostile responses from people because they wondered just how they were supposed to wash their cars if the soap, and other (engine) cleaners, were not supposed to go down the storm sewers.

I had a dejavu moment as we were WWOOFing http://www.wwoof.org/ and they had done a great job with the garlic last fall by mulching it with oat straw - but they'd imported bind weed http://www.omafra.gov.on.ca/english/crops/facts/ontweeds/field_bindweed.htm with the straw. Dito for people who have used local municipal compost and wood chips!! There is much to be said for not contaminating the water - and spreading that far and wide viw our modern just-dump-it-into-the-rivers approach to things.

I put up a metal roof at the WWOOFing farm and they were not thinking of water storage - but they should have as they're off-grid and hand pump all water and have no pond at all on the 300 acres and it's high, sandy soil so they can't easily dig a pond.

One property we just looked at was a flood area - lots of water (most of the 16 acres) but I'm not into growing rice.

One person comments on 150L/day of water per adult. That's excessive. We're 3,000L/mo for 2 adults and two 6-year olds - that's 33L/day/adult if you count both kids as a "adult". That's water for all home use (dishes, laundry, cooking, drinking). We keep about 50L of stored potable water and have another 80L in the hot water tank if need be. Our issue will be fuel for the white gas stove to cook foods. But yes, if you're catching rainwater - make sure that a chunk of it is for emergency human use.

Prior to my grandfathers death in the early 40's, I spent many childhood summer months on his Missouri farm. There was a functioning outhouse. On more than one occasion I was told "never drink the cistern water". The hand pump was OK. Water was heated on a coal burning stove. I am uncertain which water source was used for the Saturday baths and laundry. We also had an ice house. Some of the ice harvested in the winter lasted until mid summer.

Hello TODers,

Thanks for a SENSIBLE and PRACTICAL article.

I want to say a couple of things about food and water requirements for bare subsistance survival.

QUESTIONS: Could 150 litres (40 gallons approx) per adult per day be an order of magnitude WRONG?
Do we really need all those calories and RDA of vitamins to stay healthy?

When I was doing bodybuilding a decade ago the training books said I needed 3000 calories of high protein food, anabolic steroids and growth hormone. Now steroids and hormones make you real hungry and let me tell you, I COULD NOT FORCE MYSELF TO EAT MORE THAN 2000 CALORIES PER DAY, it just would not fit in my belly and I'm a six foot 200 lb man. May I propose that recommended daily allowances are completely inaccurate and no guide to successful survival whatsoever.

My best mate and I have been putting up a steel (colourbond) tool/garden shed all this week so now I'll be a real Australian bloke.

This morning we are off to the hardware store to buy a 500 gallon plastic water tank to install at the side of the shed for drinking water.

We already have 2 other water tanks that harvest runoff from our tiled house roof but some of the dye from the tiles leaches into that water making it unsuitable for drinking.

We also have an aquaculture pond that holds 1000 gallons giving us a total of 2500 gallons water storage for a 1/6 acre urban dwelling. We have no room for any more storage so THAT WILL BE SUFFICIENT TO SUSTAIN US.

Every square inch of sunny ground is currently under crop (raised beds mostly) and it is amazing how much food you can grow in a small space if you've got plenty of manure and mulch. We are still eating broad beans that were frozen about this time last year and have storage corn and green beans from last summer and storage cauliflower and brocolii from this fall. We also manage to give away food to family and freinds.

The problem engineers are having is that numbers are not really linear/absolute unless you believe them to be so or you are trying to build a structure/machine. A living organism is not a machine/structure, only machines/structures believe in the linearity/absoluteness of numbers, in THE REAL WORLD there is no such thing as a number, they are "things of the mind" and like all such mental constructs are fully deceptive.

Eg: 4 is ONLY 4 if you believe it can only be 4, with appropriate levels of Faith and Magic 4 can quite easily be 7 or (6 + 3j) if you need it to be.

Proceed with plans to be INDEPENDANT OF THE BEAST.
With Intelligence, Faith and Hard Work the world will bend to your Will.

Another question: Is Obama the ANTI_CHRIST ?
(included that one to make you Scanky Yankees Cranky) (observe the embedded KKK)

I'll put up some photos of our water storage and food production facilities on this thread later today because phoyos motivate better than strings of those mental concepts call letters.

What is your main calorie crop ? Do you use a freezer to store ?

Potato does very well here over winter, so that's one big calorie crop, stores well.

Various beans also do very well, 12 months of the year, and have a reasonable amount of calories.

Corn does very well here in the extreme heat and pest time of summer when nothing else survives. Will try to assess yield/viability with a big crop this southern hemisphere summer, although my "hunch" is that it is a little bit "space consuming".

We have freezer storage and that will be a bit more ecologically justifiable when we can afford a solar PV system and a small wind turbine. Batteries are one area of technology where I am hoping the engineers will come up with some really cool imaginary numbers soon.

50 square feet of potato and 30 square feet of broad beans. We have 3 of these potato plots in at the moment.

Potatoes are "stacked", ie, as they grow you cover them with more growing media, allowing the leaf/stem to reach no more than 4 inches in height before adding more growing media, until you have a reasonable sized (1.5 foot) raised bed. The plot pictured should yield approx 60 pounds of potatoes

Do you do animal products ?

Vegetable oil ?

How do you store the corn ?

All the eggs we can eat plus some great fertiliser, the broad beans and potatoes pictured upthread are growing on the previous years chicken run. They eat all kitchen scraps, slugs and snails but do need bought formula food for high yield. They also dig up our compost heaps for worms and slater bugs prior to putting the compost into growing media.

Freeze the corn, don't actually know if that's the best way to store it, but it seems pretty good to us.

OIL not practical with such a small area as far as I know, although we have a young olive tree and the back door neighbours have a very large olive tree which we harvest and preserve for a share. I suppose one could try to press them for oil. We get our cold pressed pure virgin organic olive oil from the buddhist temple in our suburb. They have an olive farm in the hills about 4 miles away.

On approx 1/6 th of acre we have:

Mulberry, apple, plum, nectarine, pear, almond, lime, lemon, mandarine, tangello, grapefruit, olive. We have a long driveway down to a back block, normally these type of driveways are "shared area" for both properties on a subdivided block. We managed to force a rezone to make the driveway ours when we bought the property. That gives us a micro orchard.

7 raised bed totalling 350 square feet. We stack 30 litre pots on all paved areas giving us another 50 square feet of growing area.

Baramundi from our fish pond, these are not ideal because they need special food but we have a secret strategy. We start with goldfish which manage to breed up to large numbers with no food input then we put a few baramundi in the pond and they eat the golfish then we eat the baramundi. We get fresh fish every second year.

Cabbages one per 30 litre pot, growing on a paved area.

My firsy corn patch in my first experimental "ventilated" raised bed.


It is a five minute drive to the CBD of Perth Oz, a city of about 1.2 million

We've been working on it for 10 years.

G'Day Ernie,

We use far less that the 150 litres of water per day..

Shortish showers (low pressure of course) - being off grid we don't have a dishwasher etc and our washing machine is a twin tub.. With the twin tub you start off with whites and end up with working strides etc.

I remember a documentary about some people in an arid area of Africa where they basically did everything from drinkining to washing self and clothes with a couple of buckets of water. Big culture shock for a city bound westerner , such as myself, but they had themselves organised around permanent drought and they were not short on smiles. It all boiled down to personal adaptation to what was available. I (all of us westerners) have been very spoilt by "fast, on tap, everything", but the challenge to change behaviour can be exhilarating.

We have sort of the opposite problem - thunderstorms that try to wash away the yard and saturate the foundation. Our 3 barrels and IBC tote all channel their overflow away from the house. I also raised a damp area so it would turn water towards a new catch basin (drainage grate in the ground). The catch basin connects to an underground PVC pipe that surfaces at the property line, then goes a black corrugated pipe to the drainage easement. This has halted erosion. When it does get dry, I have a gravity fed hose to water anything that's too dry. I built a low rock wall around another muddy spot that would get overflowed in rainstorms, filled it with dirt, and added a pear tree and moisture loving native flowering plants.

October 22-24, 2009 Fairfield, Iowa


anyone near here ... might be informative