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Cisterns & Rain Barrels Print E-mail


Rainwater coming off the dome can be caught in troughs and carried to your cistern. You can use the excess concrete left over when the panel seams are getting filled with concrete and make a trough around the outside edge of the slab at ground level to carry the water to the cistern.

One of American Ingenuity's clients is about to finish his cistern design for his dome to be built in Tortolla British Virgin Islands.

Rainwater can be harvested from rooftop catchments. 

The following information came from their web site

The application of an appropriate rainwater harvesting technology can make possible the utilization of rainwater as a valuable and, in many cases, necessary water resource. Rainwater harvesting has been practiced for more than 4, 000 years, and, in most developing countries, is becoming essential owing to the temporal and spatial variability of rainfall. Rainwater harvesting is necessary in areas having significant rainfall but lacking any kind of conventional, centralized government supply system, and also in areas where good quality fresh surface water or groundwater is lacking.

Annual rainfall ranging from less than 500 to more than 1,500 mm can be found in most Latin American countries and the Caribbean. Very frequently most of the rain falls during a few months of the year, with little or no precipitation during the remaining months. There are countries in which the annual and regional distribution of rainfall also differ significantly.

For more than three centuries, rooftop catchments and cistern storage have been the basis of domestic water supply on many small islands in the Caribbean. During World War II, several airfields were also turned into catchments. Although the use of rooftop catchment systems has declined in some countries, it is estimated that more than 500 000 people in the Caribbean islands depend at least in part on such supplies. Further, large areas of some countries in Central and South America, such as Honduras, Brazil, and Paraguay, use rainwater harvesting as an important source of water supply for domestic purposes, especially in rural areas.

Technical Description

A rainwater harvesting system consists of three basic elements: a collection area, a conveyance system, and storage facilities. The collection area in most cases is the roof of a house or a building. The effective roof area and the material used in constructing the roof influence the efficiency of collection and the water quality.

A conveyance system usually consists of gutters or pipes that deliver rainwater falling on the rooftop to cisterns or other storage vessels. Both drainpipes and roof surfaces should be constructed of chemically inert materials such as wood, plastic, aluminum, or fiberglass, in order to avoid adverse effects on water quality.

The water ultimately is stored in a storage tank or cistern, which should also be constructed of an inert material. Reinforced concrete, fiberglass, or stainless steel are suitable materials. Storage tanks may be constructed as part of the building, or may be built as a separate unit located some distance away from the building. Figure 1 shows a schematic of a rooftop catchment system in the Dominican Republic.

All rainwater tank designs (see Figures 2a and 2b) should include as a minimum requirement:

  • A solid secure cover
  • A coarse inlet filter
  • An overflow pipe
  • A manhole, sump, and drain to facilitate cleaning
  • An extraction system that does not contaminate the water; e.g., a tap or pump
  • A soakaway to prevent spilled water from forming puddles near the tank

Additional features might include:

  • A device to indicate the amount of water in the tank
  • A sediment trap, tipping bucket, or other "foul flush" mechanism
  • A lock on the tap
  • A second sub-surface tank to provide water for livestock, etc.

The following questions need to be considered in areas where a rainwater cistern system project is being considered, to establish whether or not rainwater catchment warrants further investigation:

  • Is there a real need for an improved water supply?
  • Are present water supplies either distant or contaminated, or both?
  • Do suitable roofs and/or other catchment surfaces exist in the community?
  • Does rainfall exceed 400 mm per year?
  • Does an improved water supply figure prominently in the community's list of development priorities?

If the answer to these five questions is yes, it is a clear indication that rainwater collection might be a feasible water supply option. Further questions, however, also need to be considered:

  • What alternative water sources are available in the community and how do these compare with the rooftop catchment system? - What are the economic, social, and environmental implications of the various water supply alternatives (e.g., how able is the community to pay for water obtained from other sources; what is the potential within the community for income generating activities that can be used to develop alternative water sources; does the project threaten the livelihood of any community members, such as water vendors?)
  • What efforts have been made, by either the community or an outside agency, to implement an improved water supply system in the past? (Lessons may be learned from the experiences of the previous projects.)·
  • All catchment surfaces must be made of nontoxic material. Painted surfaces should be avoided if possible, or, if the use of paint is unavoidable, only nontoxic paint should be used (e.g., no lead-, chromium-, or zinc-based paints). Overhanging vegetation should also be avoided.

Water Barrels

The following information came from Aaron's Rain Barrels web site

A rain barrel is a rainwater harvesting system that is connected to a down spout tube from a house or building. We make quality rain water barrels that collect, store and divert rooftop runoff during a rain shower.

An Aaron's Rain Barrels is a better designed rain barrel. We offer you our #1 selling recycled plastic barrel or a traditional whiskey barrel. Our preferred rain collection barrel connects directly to your rain gutters down spout tube, has an overflow valve and is only made from the best quality parts so they last a lifetime.

There is more to making rain barrels then just adding a spigot to a barrel. If things are not done just right your rain barrel will leak within a few weeks.

The following information came from Rain Barrel's web site:

Eric’s Rainwater Harvester

Thought you might like to know of the great success that was obtained from your excellent products. Ordered the 3p Rainus from you along with a Rain Mammoth setup. Have since obtained a FloTrue Smart Valve Rainwater Diverter that flushes the first 10 to 60 gallons of water from the roof (the amount is up to the individual). They got blown away in hurricane Katrina and are trying to re-tool for production again.

I eventually obtained one from www., the last one on the shelf. Look at FloTrue's Smart Valve Dealers page for more info. The product was inexpensive ($80) and performed excellently.

Then purchased a Katydyn Gravydyn 2 1/2" gallon drip ceramic and carbon filter from Look/search under water filters on this page for the Katydyn filter.

Had the rainwater tested by a Fort Worth, Texas microbiology water testing company and the test results came back astonishingly clean for being in the middle of a large city and using a composite roof.

  • Lead -.02 mg/liter
  • Sulfates-1.3 mg/liter
  • Nitrates- .02 mg/liter
  • Fecal Coliform - 0% none

Was also told this was at the very bottom of anywhere near the accepted parts per million. They said “drink it”.

This was very exciting for me and I share this with you as you mentioned that you were looking for an “off the grid” system to maybe offer to others. No electrical anything. If you look closely between the barrels in the picture that was sent, the Flo-True can set-up can be seen. The valve is mounted inside the “clean-out tee” at the bottom of the white pipes.

Thanks for dealing with me and offering some guidance; love your 3P Rainus filter by the way, does a nice job and my home is overhung by many trees. Have gutter leaf guards on the roof also.

Hope that Spring is coming your way and your days are a bit brighter. Keep up the good work for earth and her inhabitants. Best Rain barrel product on the market! I know, have seen many.

Maybe if your days are a bit brighter you could actually read the latest TIME magazine, April 3, 2006 Special Report on Global Warming “Earth at The Tipping Point”. Might make you feel important.

Oh, and keep up the work on the “Technorati” pages, this is where I gained a lot of initial insight on my dream of Rainwater Harvesting.


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