topic and questions, Susan.
I too am skeptical of small capacity (200
liter/50 gallon max) "rain barrels", for the reasons you mention plus a couple
more. On the other hand, if done right, I think rain harvesting has much promise
for doing environmental good.
Our local Mecklenburg County Soil and Water
Conservation Service (an excellent program that does lots of good locally, going
far beyond just rain barrels) will help people purchase home downspout rain
barrels, but I’m still not sold on them.
For small scale versions, I’d
add risk of mosquitos, especially down here where skeeters have been known known
to completely drain unwary gardeners who stepped outside at dusk in mid-summer
‘just for a second’ to pick a few cucumbers.
Also there’s the matter of
pressure. We’ve gotten used to watering from hoses where the water comes out. To
get that, you have to elevate the barrel, making for all kinds of mostly funny,
unstable and not very attractive jury rigs on cinderblocks etc – or water just
kind of oozing out that handy spigot (before it breaks off).
On the other
hand, if done right, rain harvesting can provide a way for us to use rain water
for gardens and food, and save treated (expensive) water for
I’ve actually seen some systems that seemed to work
beautifully. One stands out (I’ve got pics somewhere…darn, how do people store
pics? Another topic…), a community garden in New York City that used a linked
array of 20 55 gal (220 l) recycled cooking oil drums raised on a platform. A
big "butterfly" roof was designed to capture rain and route it to the barrels.
It was the major source of water for a garden full of fruit trees and veggies in
the middle of the city.
There’s also the "downstream" factor to consider.
Especially with all our pavement, we turn gentle rains into cataclysmic flash
floods for the fish and wildlife that live in our suffering urban creeks.
Anything we can do to check this by slowing water down is beneficial, and even
basic rain barrels help do that. In our landscapes, we can go far beyond that,
though, by mindfully considering how water and rain behave in our own garden
ecosystem, and making water part of our garden design dance.
blab on here, let me leave some links that have me thinking:
this out! Many lessons here – rainwater harvesting doesn’t have to be in earnest
utilitarian plastic barrels! Thai Jars work too (and what other ideas are out
there???)! We can learn huge amounts from the rest of the world, especially the
"developing" world. In our rush to the future, we dropped a lot of valuable
things along the way, and we gardeners are ideally suited to gathering them up
The waterworks grant from Organic Gardening Magazine (good for
them) is at:
Seattle and Dan Winterbottom
course, Seattle has great info on this. The most helpful reference on this page
for me is the article by Daniel Winterbottom, a landscape architect at U of
Washington who really understands rain harvesting, and has been using it as
water source for farmers in the developing world. Click on the Rainwater
Pics on Flickr
http://www.flickr.com/photos/serpentor/sets/1351203 – a
bunch of interesting rainwater harvesting pics
From Green Clips –www.greenclips.com
HARVESTING: RECONSIDERING AN ANCIENT TECHNOLOGY
Rainwater collection in
cisterns and on roofs, a traditional means of storing water for irrigation and
other uses, is attracting renewed interest as concerns grow about depleted
aquifers and chemically treated municipal water supplies.
harvesting systems typically include six components: catchment area, roof-wash
system, conveyance system, cistern, delivery system, and water treatment
The most common contemporary catchment areas are roofs, with
stainless steel or galvanized steel with a baked-on enamel, lead-free finish
considered the best roofing materials for rainwater collection.
figure rainwater yield: 1 inch of precipitation on 1 square foot of collection
area yields 0.6233 gallons. Gutters, downspouts, and piping convey rainwater
from the catchment area to a filtration or storage unit.
systems used solely for irrigation, filtration can be as simple as leaf screens
combined with a roof-wash system that drains particulates from the roof during
the first flush of rain. To achieve potable water quality, appropriate
filtration systems include a simple microfiltration process employing gravel,
sand, and charcoal; UV sterilization; or ozonation. Cisterns, which range from
small drums to structures storing thousands of gallons, can be made from a
variety of materials, including galvanized steel, concrete, and polyethylene.
Construction costs tend to be high (a common rule of thumb is one dollar
of construction cost per gallon of water stored), but rainwater harvesting may
become more economically feasible if municipal water costs rise. – Landscape
Architecture, Apr 00, p 40, by Daniel Winterbottom. Yield formula from: Natural
Home, May/Jun 00, p 74, by Molly Miller.
From the developing
world, a different approach:
There is also a way to utilize rain water
without contraptions (we Americans love our contraptions, though, and more power
to us – but they are not always necessary). Doing berms and natural moist areas
with adapted plants in our gardenscapes may be more effective than plastic
barrels? Check this out:
couple key ideas that caught my eye:
Just as there are many
different kinds of irrigation methods, rainwater harvesting can be accomplished
using a broad range of technologies, from very simple and very small structures
to very extensive and complex ones. Scientists with the Ben Gurion University of
the Negev, Institute for Desert Research have divided the technology into five
categories, including Micro-catchment systems, Terraced wadi (stream-bed)
systems, Hillside conduit systems, ‘Liman’ systems and Large-scale diversion
Designing a System
For rainwater-harvesting to be possible,
three basic landscape elements muxt be present:
1) The landscape surface
or soil conditions must be able to produce runoff.
2) The landscape
surface must include variations in elevation so that runoff water created during
rains will flow into and be collected by cultivated areas.
areas must have adequately deep soil horizon of a suitable structure to store
sufficient runoff for crop production.