Rainwater Catchment J Gnarly
A rainwater catchment system will be built on a house in Blue Lake California. The rainwater will be carried from the gutters to storage tanks for use in flushing the indoor toilet. Kyle Basnett and Colin Bourgeois are working on this project as part of the Humboldt State University's Engineering 305 course in Appropriate Technology.
- Design and install a safe, easy to use and maintainable rain water catchment system.
- Acquire water storage containers for 200 gallons of rainwater storage.
- Connect the rainwater catchment system to the toilet tank for a gravity fed rainwater toilet.
- Design and install devices that will ensure water damage does not occur.
The following criteria, constraints and weight of importance will help guide us through the designing and building process of this project. This list was compiled by Colin Bourgeois, Kyle Basnett and our client J Gnarly.
|Criteria||Constraints|| Weight |
|Function||Collects and stores rainwater.|| |
|Safety||Does not pose a safety risk to people or the house|| |
|Maintanence||No More than 15 min/week cleaning and maintaining|
|Budget||Spend less than $200|
|Asthetics||Needs to look nice|
|Reliability||Works every time|
|Usability||Flushes and fills like a conventional toilet. Simple to switch from rainwater fill to conventional water fill|| |
We will be utilizing the existing gutters on the house to direct the water flow. We have added the necessary plumbing to lead the collected water from the front and back gutter,to our storage tanks in the back of the house. We have placed gutter filters into the gutters to strain out the bulky material. The storage tanks are set on top of the stand that we built. The tanks are connected together on the bottom and sealed so that they will equalize. The water is then allowed to either head into the house, or into our secondary release valve. We have situated a shut off valve that can have a hose attached to it for directed water distribution. The piping into the house has a shutoff valve for the houses main water, and to shutoff our rainwater. This allows for switching between water sources depending on stored water levels.
Proposed time line
- March 2nd - Have a current list of necessary materials, and goals.
- March 4th - Have all main materials.
- March 8th - Have design refined.
- March 10th - First installation (1st trial).
- March 17th - Work on refined plan and adjust potential problems.
- March 29th - Test and discuss quality of work.
Literature Review by Kyle Basnett
This is my review on the available literature relevant, and on hand, for our rain water catchment project.
Basics on Rain Water Catchment
One of the biggest current and future economic problems that our world is facing is a shortage of drinkable water. Having clean water is vital to the health and survival of our race. A big portion of waste in regards to water usage is in the home. A huge portion of our drinkable water is literally flushed down the toilet. We are going to cut down on our use of clean water by utilizing the natural energy source that the cycle of life provides us with: rain. We will be collecting rainwater in a system that we will design and build, and transfer that water to a house's plumbing to be used to flush the toilet. Though many people are becoming more conservative in regards to using the bathroom and avoiding water waste, many people are still using much more than necessary. For the people who cannot use outdoor, eco-friendly toilets, we will do our small part to help in conservation of the increasingly limited supply of drinkable water.
Potential design difficulties
At our current level of understanding on the project our primary concern is to safely secure the storage devices in a manner that is easy to clean, understand, and that will be effective for our system. We are also aware that a more specialized and appropriate understanding is necessary for our success.
Methods of rain water harvest
Rainwater can be captured (harvested)in many ways. The most commonly used method is by roof. All kinds of roof systems can be used for capture, but roofs with a pitch are much more efficient than flat roofs. The steeper the pitch the higher the efficiency. Gravity rules. Any slope can be used to capture rainwater with vastly different levels of cleanliness, efficiency, and setup and maintenance difficulties. For areas without a natural slope, or a roof, many varieties of structures can be built for rain capture.
Designing interpretive materials
The materials that our project will be using are similar to those of other rain water catchment systems. We will be utilizing a sloped roof, with a gutter drainage system, that will transfer the gathered rainwater down the conveyance into a first flush cycle, that we will create. This will then fill our large 50 gallon storage drums that will store the water for later use.
<Downey, Nate. Harvest the rain: how to enrich your life by seeing every storm as a resource. Santa Fe, N.M.: Sunstone Press, 2010.>
<Ryn, Sim. The toilet papers: recycling waste and conserving water. Sausalito, CA: Ecological Design Press, 1995.>
<Phipps, Marcus, and Jan Brace-Govan. "From Right to Responsibility: Sustainable Change in Water ." Journal of Public Policy & Marketing September (2011): 203-219.>
Literature Review by Colin Bourgeois
This is a literature review with information important for the J Gnarly site.
Rain Water Catchment Basics
There are a differing types of rainwater catchment systems. This review will focus on using a roof for the catchment. Water will be collected from the roof of the house via gutters that are already in place. The research and literature reviewed is geared toward first flush systems and water storage. The water collected will be used for flushing the one indoor toilet in the house at the J Gnarly site.
Rain water collected by the gutters will be gravity fed via PVC pipe in to a first flush device then into 50 gal food grade storage tanks. The water then will be gravity fed as needed into existing plumbing that fills up the toilet tank so that the existing float valve in the tank controls the water flow.
Water will be stored in 50 gallon drums at a height of 5 feet, each drum when filled with water to capacity will weigh approximately 500 lbs.  With a goal of 4 storage drums, finding a suitable solution to the stands to hold the drums (totaling 2000 lbs) will be challenging.
The first flush device is used to clean the water of debris and harmful chemicals that the collected water flow into before going into the storage tanks. The device should hold one gallon of water for every 100 sq. feet of catchment surface, in this case the roof. 
The device can be a standpipe; a PVC pipe with appropriate volume using the aforementioned rate, once the standpipe fills to capacity the water will then flow into the storage tanks. At the bottom of the standpipe a drainage device lets water out at a constant trickle to ensure the diverted first flush water does not become stagnant and brackish. 
Another device used for first flush is a flush tank. The tank functions the same way a stand pipe would except that a tank is used instead when a larger volume of water needs to be flushed.
Ball valve a floating ball valve can be used in the first flush device to ensure diverted water does not mix with water flowing into the storage tank. When the flush tank or pipe fills to capacity the ball is pushed into a junction or neck in the pipe or tank and prevents water from flowing into or out of the tank or pipe so long as it is full.
Debris from the roof, bacteria, viruses and pollutants in the atmosphere. 
- Freed, Eric Corey. Green building & remodeling for dummies. Hoboken, N.J.: Wiley, 2008.
- Freed, Eric Corey. Green building & remodeling for dummies. Hoboken, N.J.: Wiley, 2008.
- Lancaster, Brad, and Joe Marshall. Rainwater harvesting for drylands. Tucson, Ariz.: Rainsource Press, 2006.
- Effects of first flush on rainwater quality http://www.irc.nl/page/29189#information
- MECHELL, JUSTIN KEITH. EVALUATION OF CONTAMINANT MIXING IN RAINWATER HARVESTING FIRST FLUSH DIVERTERS. Office of Graduate Studies of Texas A&M University. 2009.
American Rainwater Catchment Systems Association (ARCSA). 2008. Austin, TX. Draft Rainwater Catchment Design and Installation Standards.
Prasanna Egodawatta, Evan Thomas, Ashantha Goonetilleke Understanding the physical processes of pollutant build-up and wash-off on roof surfaces Science of The Total Environment, Volume 407, Issue 6, 1 March 2009, Pages 1834–1841
Not yet a complete list
- 50 gallon, food quality storage drums
- 3/4" pipe
- 3/4" 90 degree elbows
- 3/4" Valve Balls
- 3/4" T valves
- 4x4 Pressure Treated Lumber
- 2x4 Pressure Treated Lumber
- Thread Seal Tape
- Iron Wool
Tools used for Construction
- Skill saw
- Radial Arm Saw (A.K.A. chop saw)
- Impacter screw driver
- Shovel and post diggers
- Speed Square
- hack saw
- tape measure
Still in Process of adding all items.
|Quantity||Material||Source||Cost ($)||Total ($)|
|4||55 gal Food Grade Drums||Bien Padre Foods Inc.||25.00||Donated|
|3||Paint for the drums||Arcata Ace||5.39||16.17|
|11||80lb bag of concrete||McKenny's Do It Best||3.79||41.69|
|9||4x4x8 PT posts||McKenny's Do It Best||7.39||66.51|
|1||4x4x8 PT posts||McKinleyville Ace||9.99||9.99|
|1||Thread Seal Tape||McKinleyville Ace||2.59||2.59|
|1||Plug Clean Out||Arcata Ace||1.79||1.79|
|1||Iron Wool||Murphy's Markets Blue Lake||0.99||0.99|
|13||90 degree slip to slip elbows||Arcata Ace|
|6||3 way T-valves||Arcata Ace|
|4||Shutoff ball valves||Arcata Ace|
|3||gutter strainers||Arcata Ace|
|6||slip to thread adapters||Arcata Ace|
- This section is for people to submit constructive advice on improving our system, or to ask questions and give any comments to the builders.