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== Future Improvements to the System ==
== Future Improvements to the System ==

Revision as of 00:50, 11 May 2013

Engr305 Appropriate Technology page in progress
This page is a project in progress by students in Engr305 Appropriate Technology. Please do not make edits unless you are a member of the team working on this page, but feel free to make comments on the discussion page. Check back for the finished version on May 15, 2013.



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 and watering the garden. User:Kyle basnett and Colin Bourgeois are working on this project as part of the Humboldt State University's Engineering 305 course in Appropriate Technology.

Project Goals

  1. Design and install a safe, easy to use and maintainable rain water catchment system.
  2. Acquire water storage containers for 200 gallons of rainwater storage.
  3. Connect the rainwater catchment system to the toilet tank for a gravity fed rainwater toilet.
  4. 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


For this project we will be utilizing the existing gutters on the house to direct the water flow where we want it. We have added the necessary plumbing to lead the collected water from the front and back gutters, into our storage tanks in the back of the house. We have placed gutter filters into the gutters to strain out the bulky material, and a first flush to sift out most of the smaller debris. The storage tanks are set on top of the stand that we built to keep them high and level. 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.

Basic Operation

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.

Safety Concerns

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. [1] With a goal of 4 storage drums, finding a suitable solution to the stands to hold the drums (totaling 2000 lbs) will be challenging.

First Flush

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. [2]

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. [3]

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.[4]

Contamination factors

Debris from the roof, bacteria, viruses and pollutants in the atmosphere. [5]


  1. Freed, Eric Corey. Green building & remodeling for dummies. Hoboken, N.J.: Wiley, 2008.
  2. Freed, Eric Corey. Green building & remodeling for dummies. Hoboken, N.J.: Wiley, 2008.
  3. Lancaster, Brad, and Joe Marshall. Rainwater harvesting for drylands. Tucson, Ariz.: Rainsource Press, 2006.
  4. Effects of first flush on rainwater quality http://www.irc.nl/page/29189#information

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

  • 55 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
  • Silicon Caulking
  • Racket ball
  • hose clamps

Tools used for Construction

  • Skill saw
  • Radial Arm Saw (A.K.A. chop saw)
  • Impacter screw driver
  • Hammer
  • level
  • Shovel and post diggers
  • Speed Square
  • hack saw
  • tape measure
  • C-Clamp


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
14 90 degree slip to slip elbows Arcata Ace 0.71 9.23
6 3 way T-valves Arcata Ace 1.42 8.52
4 Shutoff ball valves Arcata Ace 7.19 28.76
3 gutter strainers Nate, a Friend 3.99 Trade for Labor
6 slip to thread adapters Arcata Ace 2.59 15.54
1 1/4" Copper Tubing, 6" length Personal Materials 2.99 Free
1 Stainless Steel Sheet Client Materials 2.00 Free
1 Copper wire Personal Materials .50 Free
1 Tube of Silicon Caulk Client Materials 8.79 Free
1 CPVC, PVC, ABS Cement Client Materials 6.00 Free
3 20' length 3/4" PVC Nate, a Friend 5.99 Trade for Labor
1 10' length 3/4" PVC Nate, a Friend 2.79 Trade for Labor
25 Miscellaneous 3/4" PVC fittings Nate, a Friend 35.00 Trade for Labor
1 8' strip of galvanized metal Client Materials 5.00 Free
8 Miscellaneous Pieces of Scrap Wood Personal and Client Materials 10.00 Free
Total Cost $201.78


  • This section is for people to submit constructive advice on improving our system, or to ask questions and give any comments to the builders.


Our project has come together quite nicely. We have ended with a working system and still plan on adding to and improving it in the near future. We have had a lot of fun designing and building this system and have not had to many set backs. A lot of our process was fairly simple because we did a lot of planning prior to construction. There were however a few hiccups when we were working. When we started building the base for the storage tanks it was a little difficult to get the 4x4 posts level and plumb in the ground. This is partly due to us trying to connect 3 pillars before sinking them into the ground, thinking that it would save us time. With the materials available to us it was a little difficult to do this quick and accurate so we had to slow down our process in order to end with quality work. Once we started doing the posts individually our efficiency climbed. Another problem that we ran into was when it came to the original float valve. We had pretty good head but with the current plumbing on the toilet we did not have enough psi to force the water through the system. It would flow through all of the piping, but fell short when it came to the last step. So we switched around some of the house plumbing and brought up the water pipe to give it less gravitational resistance. This also failed, and that is when we settled on switching the float to a system that requires less psi. The system now functions quite well in gathering water, and slowly but surely fills the toilet. This project fit perfectly into the rule of 3's taught in business classes. The project cost 3 times as much, and took 3 times as long as we originally thought. In the end though, we have a working system which will in fact pay itself back soon seeing as the labor was free.

Final Product

Future Improvements to the System

After a chance meeting with an experienced rainwater collection builder an inexpensive solution for increasing the psi of the system is going to be designed and hopefully implemented. The solution as it is preliminarily understood is that an empty drum or two will be placed on top of the existing drums and connected to the drums below and sealed air tight while all drums are empty of water. As the drums fill with water and decrease the amount of air space the trapped air will increase in pressure. As this design is currently understood questions arrise as to whether enough air pressure can be generated to increase water pressure substantially and secondly, will air pressure be contained while the rainwater inlet pipe does not having water flowing through it?

If enough water pressure can be generated a FluidMaster 400A model toilet fill valve will be installed so the toilet tank will fill faster and quieter.

In light of potentially being able to increase the pressure of the system by rearranging the drums and adding another drum we have decided not to install a support railing around the drums incase of earthquakes because it would be just be taken down in a matter of days and not worth the time and materials.

If the pressure increase system does not work a custom made float valve mechanism is going to be designed in the next couple months, before the rainy fall season, with the hope that it can be 3D printed and will decrease the toilet tank fill time by improving the flow rate into the toilet.

Lessons Learned

It was super helpful to leave plumbing in place with out glue until the system was ready to be tested because modifications could be made with out having to cut and replace parts.

A minimum of 2.5 psi is required to operate the toilet using a commercial toilet fill valve. The Fluid Master 400A with a low pressure rubber disc available form the manufacturer is the lower pressure requirement this team found for a fill valve. 5' 10"' is the minimum head requirement for a 2.5 psi system.

When installing posts set them in the ground and one by one instead of connecting three and trying to install them at once.

Progress Images


Contact details