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Snippet from Wikipedia: Rainwater harvesting

Rainwater harvesting (RWH) is the collection and storage of rain, rather than allowing it to run off. Rainwater is collected from a roof-like surface and redirected to a tank, cistern, deep pit (well, shaft, or borehole), aquifer or a reservoir with percolation. Dew and fog can also be collected with nets or other tools. Rainwater harvesting differs from stormwater harvesting as the runoff is collected from roofs, rather than creeks, drains, roads or any other land surfaces. Its uses include watering gardens, livestock, irrigation, domestic use with proper treatment, and domestic heating. The harvested water can also be committed to longer-term storage or groundwater recharge.

Rainwater harvesting is one of the simplest and oldest methods of self-supply of water for households, and residential and household scale projects usually financed by the user. However, larger systems for schools, hospitals and other facilities can run up costs only able to be financed by companies, organization and governmental units.

Rain water collection is a very efficient way to acquire large quantities of clean water, in some parts of the world it is the only practical way to do it.

Collecting While On the Go

When you are bugging-out, rain is an excellent source of water. Collected rain water does not need any preparation and can be collected quickly if you are properly equipped. You will only need a collection device and a container for the water, you should have both as part of your BOB. Your water bottle, hydration bladder, or other water containers should work just fine. For an ideal collector you need a large, flexible, sheet such as a tarp or poncho to collect the water from a large area and funnel it into your container. You may find that collectors occur naturally in rock formation, large plant leaves, etc… Many individuals build shelter in such a way as to act as a collector in the event or rain.

Collecting Water from at Home

Water collection is also an excellent source of water for the home, particularly in areas where wells are not practical. If you choose to collect water at home the basic needs are the same as on the go, a collector and a container. In the case of home collection both of these items should be much larger. For the collector you may want to build a dedicated collector, but one of the most practical ways to do it is with your roof. A metal roof should be employed, shingles would create far too many unwanted deposits, which would then funnel water into a cistern. A cistern is a large underground tank that is the most common way to store collected water for easy access later. Rain Barrels could also be used, but they would not hold nearly as much water and would have to be stored themselves.

Water can also be collected and stored with the use of Swale, dams, and various other features used in Permaculture. This water would be equal to water gotten from a lake or pond, and thus non potable, requiring water treatment to be used for drinking, cooking and bathing.

See Also


Brad Lancaster's wikipedia page. Brad literally “wrote the book(s)” about harvesting rainwater, although his focus centers around the homestead with very little attention given to mobile collection.

Water Self-Sufficient_Living

Water supply Water conservation Irrigation Appropriate technology DIY culture Aquifers


for rainwater storage]] Rainwater harvesting is the accumulation and deposition of rainwater for reuse on-site, rather than allowing it to runoff. Uses include water for garden, water for livestock, water for irrigation, water for domestic use with proper treatment, and indoor heating for houses etc. In many places the water collected is just redirected to a deep pit with percolation. The harvested water can be used as drinking water as well as for storage and other purpose like irrigation.


Rainwater harvesting provides an independent water supply during regional water restrictions and in developed countries is often used to supplement the main supply. It provides water when there is a drought, can help mitigate flooding of low-lying areas, and reduces demand on wells which may enable ground water levels to be sustained. It also helps in the availability of potable water as rainwater is substantially free of salinity and other salts.


The concentration of contaminants is reduced significantly by diverting the initial flow of run-off water to waste.<ref>New Scientist, 3 April 1999</ref> Improved water quality can also be obtained by using a floating draw-off mechanism (rather than from the base of the tank) and by using a series of tanks, with draw from the last in series. The stored rainwater may need to be analyzed properly before use in a way appropriate to ensure its safe use

The quality of collected rainwater is generally better than that of surface water. Contamination is always possible by airborne dust and mists, bird feces, and other debris, so some treatment may be necessary, depending on how the water will be used.

System Setup

Rainwater harvesting systems can be installed with minimal skills. The system should be sized to meet the water demand throughout the dry season since it must be big enough to support daily water consumption. Specifically, the rainfall capturing area such as a building roof must be large enough to maintain adequate flow. The water storage tank size should be large enough to contain the captured water.

Rain water harvesting by freshwater flooded forests

, Bangladesh]] Rain water harvesting is possible by growing fresh water flooded forests without losing the income from the used /submerged land.<ref>Rain water harvesting by fresh water flooded forests</ref> The main purpose of the rain water harvesting is to utilize the locally available rain water to meet water requirements throughout the year without the need of huge capital expenditure. This would facilitate availability of uncontaminated water for domestic, industrial and irrigation needs.

New approaches

Instead of using the roof for catchment, the RainSaucer, which looks like an upside down umbrella, collects rain straight from the sky. This decreases the potential for contamination and makes potable water for developing countries a potential application.<ref>

</ref> Other applications of this free standing rainwater collection approach are sustainable gardening and small plot farming.<ref>


A Dutch invention called the Groasis Waterboxx is also useful for growing trees with harvested and stored dew and rainwater.



Around the third century BC, the farming communities in Baluchistan (in present-day Pakistan, Afghanistan and Iran), and Kutch (in present-day India) used rainwater harvesting for irrigation.<ref>


In ancient Tamil Nadu (India), rainwater harvesting was done by Chola kings.<ref>

</ref> Rainwater from the Brihadeeswarar temple was collected in Shivaganga tank.<ref>

</ref> During the later Chola period, the Vīrānam tank was built (1011 to 1037 CE) in Cuddalore district of Tamil Nadu to store water for drinking and irrigation purposes. Vīrānam is a

long tank with a storage capacity of


Rainwater harvesting was done in the Indian states of Madhya Pradesh, Maharashtra, and Chhattisgarh in the olden days

. Ratanpur, in the state of Chhattisgarh, had around 150 ponds. Most of the tanks or ponds were utilised in agriculture works.

Present day

  • Currently in China and Brazil rooftop rainwater harvesting is being practiced for providing drinking water, domestic water, water for livestock, water for small irrigation and a way to replenish ground water levels. Gansu province in China and semi-arid north east Brazil have the largest rooftop rainwater harvesting projects ongoing.
  • In Bermuda, the law requires all new construction to include rainwater harvesting adequate for the residents.
  • The U.S. Virgin Islands have a similar law.
  • In Senegal and Guinea-Bissau, the houses of the Diola-people are frequently equipped with homebrew rainwater harvesters made from local, organic materials.
  • In the Irrawaddy Delta of Myanmar, the groundwater is saline and communities rely on mud-lined rainwater ponds to meet their drinking water needs throughout the dry season. Some of these ponds are centuries old and are treated with great reverence and respect.
  • In the United States: until 2009 in Colorado, water rights laws almost completely restricted rainwater harvesting; a property owner who captured rainwater was deemed to be stealing it from those who have rights to take water from the watershed. Now, residential well owners that meet certain criteria may obtain a permit to install a rooftop precipitation collection system (SB 09-080).<ref>

    </ref> Up to 10 large scale pilot studies may also be permitted (HB 09-1129).<ref>

    </ref> The main factor in persuading the Colorado Legislature to change the law was a 2007 study that found that in an average year, 97% of the precipitation that fell in Douglas County, in the southern suburbs of Denver, never reached a stream—it was used by plants or evaporated on the ground. In Colorado you cannot even drill a water well unless you have at least 35 acres. In New Mexico, rainwater catchment is mandatory for new dwellings in Santa Fe.<ref>

    </ref> Texas offers a sales tax exemption on the purchase of rainwater harvesting equipment. Both Texas<ref>

    </ref> and Ohio allow the practice even for potable purposes. Oklahoma passed the Water for 2060 Act in 2012, to promote pilot projects for rainwater and graywater use among other water saving techniques.<ref>


  • In Beijing, some housing societies are now adding rain water in their main water sources after proper treatment.
  • In Ireland, Professor Micheal Mcginley established a project to design a rain water harvesting prototype in the Biosystems design Challenge Module at University College Dublin


  • In the state of Tamil Nadu, rainwater harvesting was made compulsory for every building to avoid ground water depletion. It proved excellent results within five years, and every state took it as role model. Since its implementation, Chennai saw a 50 percent rise in water level in five years and the water quality significantly improved.<ref>


  • In Rajasthan, rainwater harvesting has traditionally been practiced by the people of the Thar Desert. There are many ancient water harvesting systems in Rajasthan, which have now been revived <ref>

    </ref> Water harvesting systems are widely used in other areas of Rajasthan as well, for example the chauka system from the Jaipur district.<ref>


  • At present, in Pune (in Maharashtra), rainwater harvesting is compulsory for any new society to be registered.
  • An attempt has been made at Dept. of Chemical Engineering, IISc, Bangalore :// to harvest rainwater using upper surface of a solar still, which was used for water distillation<ref>



  • The Southwest Center for the Study of Hospital and Healthcare Systems in cooperation with Rotary International is sponsoring a rainwater harvesting model program across the country. The first rainwater catchment system was installed at an elementary school in Lod, Israel. The project is looking to expand to Haifa in its third phase. The Southwest Center has also partnered with the Water Resources Action Project (WRAP) of Washington D.C. WRAP currently has rainwater harvesting projects in the West Bank.
  • Rainwater harvesting systems are being installed in local schools for the purpose of educating schoolchildren about water conservation principles and bridging divides between people of different religious and ethnic backgrounds all while addressing the water scarcity issue that the Middle East faces.<ref>


Sri Lanka

  • Rainwater harvesting has been a popular method of obtaining water for agriculture and for drinking purposes in rural homes.
  • The legislation to promote rainwater harvesting was enacted through the Urban Development Authority (Amendment) Act, No. 36 of 2007.<ref>


  • Lanka rainwater harvesting forum<ref>

    </ref> is leading the Sri Lanka's initiative.

South Africa

  • The South African Water Research Commission has supported research into rainwater harvesting. Reports on this research are available on their 'Knowledge Hub'.<ref>


  • Studies in arid, semi-arid and humid regions have confirmed that techniques such as mulching, pitting, ridging and modified run-on plots are effective for small-scale crop production.<ref>


United Kingdom

In the United Kingdom, water butts are often found in domestic gardens to collect rainwater, which is then used to water the garden. However, the British government's Code For Sustainable Homes encourages fitting large underground tanks to new-build homes to collect rainwater for flushing toilets, washing clothes, watering the garden, and washing cars. This reduces by 50% the amount of mains water used by the home.


  • In 2012, American artist Michael Jones McKean created an artwork in Omaha, Nebraska at the Bemis Center for Contemporary Art that created a fully sustainable rainbow in the Omaha skyline. The project collected thousands of gallons of rainwater storing the water in six, daisy-chained 12,000 gallons tanks.<ref></ref> The massive logistical undertaking, during its 5 month span, was one of the largest urban rainwater harvesting sites in the American Mid-West.

See also


From Survival and Beyond

Visitors to the farm are usually surprised to learn that we water the entire garden and landscape with reclaimed rain water. Our system, which collects and stores rainwater from our barn’s metal roof, provides 100% of our annual watering needs. The best part, it was extremely easy to install, and can be inexpensively adapted to almost any home, shed or roof with a gutter.

We spent the past week hooking our tanks back up from winter storage – and within 24 hours - we had just over 150 gallons stored from a single rain. It’s been over a year now since we first completed the rainwater collection system – and I honestly don’t know how we survived without it.

It gives us access to free water, and with our two plastic tote tanks, can collect as much as 550 gallons from a single downpour. And that’s only using rain from the back portion of the roof! This spring, we will add a third tank fed by the front gutter – increasing our storage to just shy of 900 total gallons – enough to handle our watering needs for nearly two months of complete drought.

How it works:

Our system starts with the rain coming into simple gutters and downspouts

Through a simple in-line diverter – the rainwater is carried to our main capture tank

The water then empties into our main storage tank

We quickly filled almost 150 gallons from a single rain last week, the day after we hooked the totes back up.

A second tank sits above the garden for watering all of the plants with simple gravity and a hose

We connect a standard garden hose to the tanks with a simple threaded adapter

The system collects rain water from a simple adapter made to fit our existing barn’s gutter. The barn has a standard gabled metal roof measuring 13 wide’ x 32′ long on each side. A 32′ section of guttering runs along the bottom of each side of the metal roof, slanted slightly to carry all of the water to the eastern side of the barn. From there, both sides empty into standard downspouts.

The front downspout (not used currently), runs down and out to the field for normal drainage. On the back downspout however, we installed a simple 2-way in-line diverter (See Picture). When the metal lever is slid to the left, rain water is diverted into a 275 gallon storage tank located below the downspout. When all tanks are full, the switch can be slid back for normal drainage.

From the main storage tank, we pump and fill a second 275 gallon tank installed above our garden. With that, we can water all of our plants quickly, using gravity and a standard garden hose connected to the tank.

To increase capacity and mobility, we are adding a second diverter to the front gutter this year. That will fill a 3rd tank mounted on wheels – giving us the ability to pull water anywhere it’s needed with our tractor. That will be a huge time saver when it comes time to water the newly planted grapevines and fruit trees on the hill this year.

Here is a look at the system’s components and cost:

Totes: $40 each We found ours for $40 each after searching on Craigslist. You can also check with local food plants that may receive their raw materials in them. One word of caution – make sure you know what was originally in your tanks and that it is safe. Our tanks were used to hold maple syrup and molasses – simple food products that can be cleaned out and re-used. You will want to avoid using tanks that held harsh chemicals. Most tanks come with a 6″ threaded cap on top, and a 2″ threaded outlet valve at the bottom. You can convert the bottom 2″ valve to accept a standard garden hose with a few adapters found at your local hardware store.

Diverter Switch : $15 You can find standard gutter diverters at your local home improvement store for about $15 – they install in minutes with rivets or screws.

Threaded Valve and Hose Adapter: $15 Your local plumbing or hardware store can hook you up with a simple threaded connection valve to convert the 2″ drain at the bottom of your tank to handle a regular garden hose. We also installed a ball valve ($10) on our tank for an extra shut off point.

A couple of final notes on collecting and using rainwater:

Keep It Dark: You will want to keep the water from getting direct sunlight to keep algae from growing in the stagnant water. Algae can only grow if there is light. If your tank is translucent like ours, you will want to cover it. We use a black covering like a grill cover to cover them up once the sun and algae become a problem. Not only does it dress it up, but it keeps the water and the flow line crystal clear. For the pictures here, we have the covers off to show the tanks.

Keep It Covered: No matter what system you use to store your water, you will want to keep closed. Water that sits is an open invitation to mosquito larvae . Our totes came with 6″ caps and lids on the top. We simply cut out the hole for the downspout, and then sealed the edge with some inexpensive foam.

Know What To Use The Water For: We only use our reclaimed water for watering plants or washing off equipment, etc. Since we do not treat it in any way, we do not use it for drinking.

Check to make sure your allowed to collect rain water. Although it sounds crazy, in some states out west you are not allowed to collect rain water, as the water rights still belong to the state. So to be on the safe side, check with your local or state government to make sure it’s legal where you live.

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rainwater_harvesting.txt · Last modified: 2020/03/12 18:37 (external edit)