CCAT rainwater catchment system
 Spring 2008 content
Humboldt State University's Campus Center for Appropriate Technology (CCAT) was started in 1978 and has been going strong since. With three live in students per year, and 18 student employees, CCAT is a “live in demonstration home” where the students of Humboldt State University and the local community actively partake in creating and maintaining a home in a sustainable way, by incorporating many aspects of Appropriate Technology.
CCAT is in need of a reinstallation of their rainwater catchment system. A system had been installed at the original Buck house, but due to construction and relocation, it was dismantled. With many supplies ready for reuse, and the advantage of hindsight, it is now time to reinstall an efficient and aesthetically pleasing rainwater catchment system. Also, the CCAT house has just recently (January 2009) finished installing a new metal roof that will work wonderfully for a rainwater catchment system.
 What an Opportunity!
With CCAT striving to be a live-in demonstration of a sustainable home, and being located in coastal Humboldt County, California, it is just waiting for the water flowing out of the downspout to be redirected into a storage tank for later use for watering in the garden, the greenhouse that is being built, and any other needs except for drinking.
Two students from Spring 2008 ENGR 305 began working on the rainwater catchment system, but it was not completed. One student, Lauren, in Spring 2009 ENGR 305 class continued the work on this project. Once the plan was laid out, the complete construction of the system took place. The opportunity to learn about the application and installation of this type of system will be further spread to those who visit CCAT. There, people will be able to learn directly about how the system works through interpretive signs and other literature. As such, this project will benefit not only those who live in CCAT, but anyone who visits the demonstration home, as well as through this site for more information.
- Because CCAT is a demonstration home, the system should look well built and maintained for the public. It must also be have a non-intrusive design, and be out of the way.
- Initial cost should be reasonable for this type of system, especially since the main tank is already purchased. Hopefully, many materials will be found that are not in use, but can be reused, so as to help keep the expense as low as possible.
- The system needs to be able to withstand the weight of the water in the storage tank when it is full, and the tank should be secured so it won't blow away when it is empty. Care must be taken to ensure the tank will be stable when it is full and empty. It must be made well so that there will be little maintenance required later on, and it will be able to last a good amount of time for the CCAT house.
- Educational Value
- The system must have some educational value for the public. Again because of the CCAT house being an educational demonstration home, the system will have an education poster that explains the system as a whole, and how other community members may pursue their own construction if desired.
- The retained water needs to be easily accessible for daily agricultural use. The tank needs to be sited in such a way that creates the maximum amount of head to decrease the amount of pumping necessary to move the water uphill.
- Functional Design
- It has to work. The tank must not leak, everything must work and be able to be maintained easily. The tank must be accessible and out of the way. The filter system must work, and the overflow should be directed to a useful area, while the water stored is able to be accessed easily as well.
- Purity of Water
- The first flush system must also work well by rejecting the first amount of rainwater, keeping it free of dust, debris, bugs, and dirt, so that the water is as pure as possible.
- CCAT approval
- The rainwater catchment system is designed especially for CCAT's water needs. It is important to make it to help the house and surrounding area, while being able to expand on the system and make changes as needed later on, as they arise.
CCAT has a tank already which will be used for this project. It is 7 feet tall, and 5 feet in diameter. This results in about 1500 gallons, which weighs about 12000lbs. when filled. We will need to excavate an area were the tank is to be placed. Originally, we thought of putting a 6ft x 6ft x 8in concrete pad down to support the tank. However, it was decided that for tis project we would not use concrete. Instead, I dug down about 8" in the area where the tank would be placed. Then I compacted the Earth down, put a layer of bricks (approximately 4" thick)on top, and then about 2" of gravel on the top of the bricks to support the tank.
There was a good deal of debate and concern over where the best place for the tanks location would be. It was finally decided that the best location would be outside the main entrance of the CCAT home, near the bike rack, and directly next to the tires. Though this spot is obvious to the public, it is not in the way of any foreseeable future projects, and will attract attention to the project and heighten peoples awareness of rainwater harvesting. The tank is up high, and it will be easy to attach a hose to it, so that access to the water for gardening purposes is very accessible. Th tank does not get any shading in its location, which is often considered a more ideal situation to help prevent heating, and additional leaching of chemicals through the plastic.
 First Flush Catchment System
After a few different attempts to create a first flush, I found a system that has seemed to work well so far.
The collected rainwater will be gathered in the roof gutter and then pass through a small leaf catcher that is meant to separate the larger debris from going into the piping. Then the PVC piping will carry the water down towards the tank. Then it will reach the first flush device, where the water will fill a small 15 gallon tank that I purchased at Resale Lumber Products. The water will flow into the small tank until it fills. Then there is a small racquetball that is held up by a small piece of wire to keep it from falling into the tank. When it becomes full, the ball will move up through the clear piping piece. Then there is a ABS piece that converts the piping from 3" to 2" where the ball will fill up this smaller space. The water will then continue to flow and be diverted into the large 1500 gallon tank.
This will allow any smaller leaves, bird droppings, and general sediment that may have built up on the roof to be initially diverted into this flush system, so that the clean rainwater can be stored in the large tank.
To size the amount of water that should be used for a first flush: It is estimated that for every 1000 square feet of collection surface, the first flush should divert a minimum of 10 gallons.(Kinkade- Levario) This is a standard rule of thumb that usually works. For this roof the surface area was approximately 49' X 32', equaling 1568 ft2, so a 15 gallon tank seemed most appropriate.
 Delivery System
The Delivery system is simple, a length of 3” PVC pipe directed from the Roof Washer to the First Water Catchment System. I used some ABS piping pieces for connectors also( these are the black ones pictured). I put up a 4" X 4" cedar post into the ground next to the cement curb driveway to keep extra support for the piping.
 Roof Washer
The roof washer is mounted to small pieces of wood attached to the side of the housing. I used a small recycled detergent bucket and cut it at an angle, then placed a screen on top of it. To secure the screen I put four small hitch pins into the sides so that it would be possible to remove. This is meant to keep the larger debris out of the system. Then I put in the 3" PVC coming out of it which would bring the water down towards the first flush.
Budget: This is the budget for what was spent on this project.
|Qty||Material Needed||Source||Cost||Total cost|
|1||1500 gallon Tank||CCAT||Already available $0||$0|
|1||20 ft. 3" PVC||Piersons Hardware||Donated $0||$0|
|1/3 yard||#2 Rock||Wes Green Landscape Materials||$40.00/yard||$13.33|
|1||15 gallon bucket||Resale Lumber||$25.00||$25.00|
|2 ft.||1/8” Screen filter||Hensel's ACE Hardware||$2.00/ft.||$6.62|
|1||Hose bib attachment for 15 gallon tank||Resale Lumber Products||$18.90||$18.90|
|1/2 ft.||Tube Spa Piping||Hensel's ACE Hardware||$4.49/ft.||$2.25|
|1||Silicone Caulk||Hensel's ACE Hardware||$4.99||$4.99|
|1||Plastic Funnel||Hensel's ACE Hardware||$7.49||$7.49|
|1||3" Bulk head fitting||ACE Hardware- Thrifty||$30.50||$30.50|
|2||5x7 tin shingle||Piersons||$.39||$.78|
|1||ABS 90 degree elbow||Piersons||$5.75||$5.75|
|2||Shelf and Rod bracket||Piersons||$2.99||$5.98|
|1||no-kink faucet 3/4in Male IPS||Piersons||$5.95||$5.95|
|1||fasteners bolts screws and nuts||Piersons||$1.69||$1.69|
|1||ABS 3" adapter||Piersons||$4.19||$4.19|
|1||Strong-tie post cap/base||Piersons||$3.34||$3.34|
|1||Bushing PVC 1.25M/4FPT||Piersons||$2.79||$2.79|
|1||power pro 10x 3 1/2||Piersons||$4.49||$4.49|
|1||ABS knockout closet flange||Piersons||$2.75||$2.75|
|1||Front Elbow Galvnz||Piersons||$1.99||$1.99|
|1||ABS 3" cleanout adapter||Piersons||$3.69||$3.69|
|1||ABS 90 degree elbow||Piersons||$3.99||$3.99|
|1||flexible coupling 3x3||Piersons||$6.99||$6.99|
|1||flexible coupling 3x 1 1/2||Piersons||$7.49||$7.49|
|2||fasteners bolts screw and nuts||Piersons||$1.69||$3.38|
|1||4x4 cedar post||Piersons||$29.43||$29.43|
|1||ABS coupling||West Coast Plumbing||$2.49||$2.49|
|1||ABS sanitary tee||West Coast Plumbing||$7.89||$7.89|
|3||ABS coupling 3x2||West Coast Plumbing||$3.95||$11.85|
|1||ABS pipe||West Coast Plumbing||$.79||$.79|
|1||ABS pipe||West Coast Plumbing||$1.79||$1.79|
|2/2||Hitch pins||Hensels ACE||$.19/ .23||$.84|
|1||approximate total tax||all stores combined||$19.96||$19.96||Total: $281.79|
 Lessons Learned
Through out this project I made some unnecessary mistakes and came across issues that wasted time and money, but I guess that is all part of the learning process. To begin with, I had very little experience building and none with rainwater catchment so I found myself second guessing my choices all the way through. The location of the tank was the first obstacle that I encountered, and it was finally decided that it should be put up higher so it could access more locations for the water use. I went through a couple of different designs on the first flush system, and I feel comfortable with the end result of what was shown here, but I had ended up getting some materials in the meantime that went unused. This included extra piping that was donated by Piersons, and later returned, as well as a bucket and funnel that was going to be used for an earlier design version of the the first flush that ended up going to waste. Hopefully it will find a purpose and use in something else in the future! Lonny, my instructor ended up giving me a contact of his- Cody- who proved to be incredibly helpful in both the design and construction. I feel like it was important to have someone else to work with on a project like this, and would recommend others to have another head and pair of hands to help out! Thanks so much for all your help Cody!
Plastic Appropriateness: I used a lot of plastic through this project, which is an unsustainable material, but I could not find anything else that would work as well and was available and within cost.
Aesthetics: Due to time constraints near the end of the project, and my own time management problems, I was not able to make it as aesthetically pleasing as I had originally hoped. I still want to paint the piping and the large catchment tank. Then I would be interested in putting some grape vines or peas along the piping, as the older picture shows from the previous catchment system. I think that would be wonderful and help to make it more pleasing to the eye.
I really enjoyed doing this project, even though it was incredibly frustrating at times. However, I feel that the project has a good end result and will work well when the rains start up again next season, providing CCAT with an additional appropriate and sustainable resource for water. I would recommend everyone to look at their own local weather conditions and see if a rainwater catchment system may be appropriate for your needs!
I also want to thank Lonny and Cody for all their help with this project. They were both essential elements to it, and without Cody I would have had a very difficult time making it as sturdy as it turned out! Infinite thanks to you both.