Thursday, January 14, 2010

Rain Water Harvesting (RWH) Cheap & Easy

Some frequently asked questions:

1. How do you harvest rainwater?
As amazing as it sounds, this is a question that comes up often. It must be theword harvest that is causing the confusion.

Per Webster’s dictionary harvest is defined as 1) to gather in or 2) to accumulate a store of. Consequently to harvest rainwater means to gather it in.

In my Great Aunt’s house in Maine, this was done with an old wood barrel. It was put beside the house and rainwater drained into it. We would use this water to drink, clean the dishes and everything else you can think of. Today it can still be caught with barrels, large and small, but I would advise against drinking it straight out of the barrel.

2. Where do you get the water?
Fortunately it comes FREE from the sky. They still have not figured out a way
to privatize rain yet. Although I am sure someone is actually thinking about
those air space rights.

3. What is the best way of harvesting rain?
Catch it in anything that holds waters. Many landscape or garden stores can
tell you where to buy barrels. Here in Austin we have a wide variety, with
some selling new barrels and other selling barrels that have been recycled. In
the Austin yellow pages I found them by calling a few landscapers and even one of the gutter installers advertised rainwater collection. Some cities offer
incentives, so also check with your local water company.

Once you have a container, simply put the barrel beneath where the rainwater runs off your roof and you have started harvesting.

Look for barrels that have a faucet attachment where you can attach a hose to use the captured water for your yard.

If you want to build your own barrel a great tutorial is at: How to Build a Rain Barrel

4. Why should I harvest rainwater?
Good question and probably the answer is going to be different for different folks. Some will like the idea of not paying the utility company for something that is FREE. Or maybe it is because rainwater is typically better for the plants. Or it could be that you don’t like big bond issues to pay for new water treatment plants. There are lots of possible reasons.

With me it was a little bit of all the above. But also it was a project I could do personally and knew it would have a net positive impact on the environment. My system makes me feel great when I am out watering or just looking at our

5. Do I need pumps to harvest rainwater?
Maybe. If you just have a small barrel and you are using an attached hose or
soaker line, no pump is likely required. If you have a barrel or tank that is
above ground level by a just a few feet, and you are on a flat piece of land, and have a small yard; probably no pump will be needed.

If your tank is at ground level and you need to move the water up any slope then you will likely need a pump.

However, sometimes you can get enough water pressure in a closed-looped water collection system to supply the pressure required, even to drive a sprinkler system. Consult a local specialist to determine what is going to work for you.

6. Can I use drip irrigation or soaker hoses with a rainwater?
Yes, but I recommend you install an inexpensive line filter.

Most irrigation stores sell inline sprinkler filters. This is a simple device that screws into the lines prior to your irrigation system and cleans out the large leaves and other stuff (i.e. sometimes referred to as particulates) out of the water so it does not clog your lines. Check out the vendors page for information on several inexpensive filters.

7. How big a yard can I water?
It depends, simple question with no simple answer. Can you have rain barrels at various places around the yard? How much rain can you capture? What type of plants do you have? How much do you want to spend on tanks?

The Austin Wildflower Center has 2 - 25,000 gallon (i.e. 7.5 - 94,625 liters)
tanks and 3 cisterns. They estimate they can capture up to 300,000 gallons
(i.e. 1,135,500 liters) a year and they estimate their system meets 10-15% of
their annual needs. The Austin Wildflower Center covers 279 acres and displays over 500 species of native plants and has become a popular destination for knowledge-seeking gardeners and nature-loving tourists.

As you can see, systems can be very large and water an extremely large area. It is just a matter of how much you really, really want to capture and how much you want to spend.

8. How big are rain barrels?
Thanks for the soft ball question, I needed it. Rain barrels vary in size from a few gallons/liters to about 100 gallons (i.e. 378 liters). Most barrels are around 50-60 gallons (i.e. 189 - 227 liters).

Rainwater tanks run from several hundred gallons/liters to many thousand gallons (i.e. 7,000 – 75,000 liters).

My tanks are about 2,000 gallons each (i.e. 7,570 liters each).

9. I want more pressure, how should I raise it?
Raising your barrel or tanks or by installing a pump. Every foot you raise your
storage tank increases the pressure about 0.433 psi or less because of pressure loss due to friction (1 psi ~ 3.21 feet of fresh water head). It generally takes only a few feet to be able to use a hose or drip system, but it takes a lot to run a sprinkler. Raising your rain barrel can be a quick and cheap way to increase your pressure.

10. Can I water my grass with rainwater?
Yes, but grass usually takes a lot of water. A typical lawn requires about 3,000 gallons (i.e. 11,355 liters) a month. This means you would need some large tanks to hold the water, especially in drier climates. Additionally, you would need a large surface area to capture the rain.

However, rain barrels can and should be used to augment your watering. This
will cut your watering bill and be better for your grass.

I recommend before going with big tanks to water your lawn you look at reducing your outdoor water consumption. Going to local vegetation, drought hearty plants and then installing either drip irrigation or soaker hose will reduce your water consumption. It will be less costly, since you then need smaller tanks.

But remember, rainwater is still free.

Ten Strategies to Promote Rainwater Harvesting

by Hari J. Krishna, Ph.D., P.E., P.H., ARCSA Founder & Past President

In the 1980s and early 90s, most people, especially in urban areas were unaware of what rainwater harvesting (RWH) meant and why there would be a need to collect rainwater. It took an enormous amount of effort working with and speaking to local communities, organizations and state agencies to publicize the need for and benefits of RWH. Based on my experience with RWH during the past 20+ years, I offer the following strategies that can be utilized to promote the technology in your respective state or region.

1. Education. Education includes both formal and informal instruction and learning. Formal education refers to classroom teaching in schools, vocational colleges and universities, while informal education involves the discussion of and seminars about RWH to citizens, local groups, and at community events. Both types of education are needed to promote RWH technology. Working with middle schools and high schools, and possibly through class projects, the benefits of RWH can be imbibed into the minds of young students, who in turn, can apply the technology at home with their parents. I have had experience with people contacting me for more information on RWH, because their children had first learnt about it at school.

Colleges and Universities must develop RWH courses for students in disciplines such as natural resources, environmental sciences, architecture and engineering. It is important to have young professionals with academic training in RWH to design such systems in their professional careers. The Texas Manual on Rainwater Harvesting is a good first source of material for developing RWH courses. The Texas Manual is available on-line at
Developing curricula in RWH for vocational schools will benefit those who intend to serve as technicians in installing and maintaining RWH systems. Lane Community College in Oregon is a good example of vocational instruction in RWH.

2. Training. For those already in the workforce, training courses such as those being offered by ARCSA can be very useful. The state land-grant universities have a vast network of engineering and agricultural/cooperative extension services in the country that can and should organize training in RWH. Since their primary role is to disseminate knowledge, this would be an ideal field in which to provide training. Again, the Texas Manual could be modified and applied to various States. National, state and local governments could also initiate training for their staff in order for them to become familiar with RWH. I had the pleasure of assisting with a short training program on RWH that was organized by the Canadian government, primarily to provide their environmental staff and others with information relating to RWH systems.

3. State and/or Regional Chapters of ARCSA. It would be very helpful to develop state or regional chapters throughout the country to focus on RWH in their respective areas. Local or regional organizations would be ideal in developing RWH publications and manuals tailored to their specific needs and climatic conditions. Local chapters can organize seminars, invite public officials and others to emphasize the value of RWH in meeting local water needs. In addition, State chapters and their members can communicate with local officials and their elected representatives in promoting RWH in their region. Also, regional organizations and their members can be invaluable in strengthening the knowledge base for ARCSA.

4. Demonstration Facilities. It is a good idea to install RWH systems at public facilities such as schools, libraries and community centers even if there is not much of a profit for the installer. Once people see the benefits of RWH, there will be enough publicity generated, and would likely help the installer in growing his or her business. In some cases, there may be limited funds available for capital expenses and not enough for labor, but that should not discourage those venturing into the RWH business. New businesses may have to invest many hours of volunteer effort in order to be recognized and to ultimately become successful.

5. Legislative Support. This is one key area that can help significantly in the growth of RWH in any particular region. Local chapters can hold seminars or demonstrate RWH systems, and invite legislators and other elected representatives to visit and become familiar. When we organized the first ARCSA conference in Austin, I was pleased that the then House Natural Resources Committee chairperson accepted our invitation to inaugurate the conference. Other legislators, a large number of state agency officials and local residents also attended the conference. Several legislative initiatives in support of RWH have been undertaken in Texas. These include Senate Bill 2, that provided sales tax exemption for all RWH equipment purchased in Texas, and House Bill 2430 that created a state RWH evaluation committee. Even as I write this paper, the omnibus RWH bill HB 1818 is being filed in the Texas state legislature today.

6. State Agency Assistance. Along with legislative support, it is necessary that the cooperation and assistance of state agencies be gained in support of RWH technology. All 50 States have government agencies that are responsible for water and environmental issues affecting their respective states. The Texas Manual on RWH published by the Texas Water Development Board (TWDB) could be used as an example to obtain funding for similar publications from other state agencies. The link for the TWDB’s RWH webpage is . Inviting state agency officials to RWH workshops and conferences would be a good way to gain their attention and support.

7. Local Government Support. Similar to state agencies, most cities and many counties have departments that deal with water conservation and environmental issues. It would be helpful to meet with local government staff and convince them that RWH saves water, and that the technology can ultimately help the city in meeting their peak water demand. The City of Austin is a good example for promoting RWH. Their water conservation website is

8. Availability of Credit. The RWH community should familiarize bankers and other mortgage lenders with RWH technology, so that they would be comfortable in providing loans to homeowners, when needed. Even if architects and engineers design a good RWH system, if a homeowner cannot secure a loan for his home and the RWH system, the project may be failure. It is therefore always a good idea to keep local lenders and their agents informed about RWH technology, by inviting them to seminars and demonstrations.

9. RWH Equipment Sourcing. Many customers prefer to purchase the equipment they need for their RWH system from a single source, rather than having to shop for components in various places. Unless a homeowner has plenty of free time available,
he or she would prefer a ‘turn-key’ type of job, where a single contractor completes the entire job. It is even better if a designer, equipment retailer and installer could work together in providing a complete RWH system that may be needed by a purchaser. The goal should be to make it easy for the purchaser to obtain and install his or her RWH system. This will go a long way in making RWH technology popular in a new area.

10. Cost Competitiveness. Regardless of how well a RWH system may be designed and installed, if the complete cost of the RWH system would be much higher than an alternative that is available to the owner, he or she may not choose the RWH system. RWH systems should be cost-competitive with well water systems as well as other surface water systems. As costs of municipal water increase, there may be a greater demand for RWH systems in urban locations. However, in order to popularize RWH systems in new areas, those involved in designing and marketing RWH systems should be willing to forego higher profit margins per unit, in favor of greater and more widespread demand for their products.

Notwithstanding all of the above, the single most important pre-requisite for promoting RWH is one’s absolute belief in and dedication to this technology. You should first convince yourself about the benefits of RWH, and then be able to convince others around you that this is a valuable yet inexpensive technology for the conservation of our precious natural resources.

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