Video[edit | edit source]

The project was done for Cal Poly Humboldt's Appropriate Technology class of Spring 2018.

Abstract[edit | edit source]

Upgrading the Rainwater Catchment system will involve several factors. First will be emptying out the catchment and first flush tanks and thoroughly cleaning all debris. It will involve taking apart all pipes, cleaning out debris, and reinstalling the pipe on the other side of the driveway as to not obstruct the driveway. Posts will be put into the ground to support the pipes and grapes will be grown at the foot of the posts in order to make the most use out of the posts. The catchment tank will also be rotated 180 degrees in order for the hose attachment to be used at an easier angle for CCAT co-directors and community members.

Background[edit | edit source]

Engineering 305 students will be fixing the current Rainwater Catchment system currently at Cal Poly Humboldt's Campus Center for Appropriate Technology.The current rainwater catchment system was built by previous engineering 305 students but is currently not in use due to several issues.

Problem statement[edit | edit source]

The objective of this project is to make the rainwater catchment system usable and practical as a form of demonstration on water collection and conservation. This objective should be fulfilled by fixing the current problems of the current non functioning rainwater catchment system. The main problem to the system is that people keep turning off the drain for the first flush of catchment which means the dirty water is not draining and is clogging the system. Another issue that will be resolved is the problem of spacing. The pipes currently cross the driveway and obstruct the walkway for pedestrians.

Evaluation Criteria[edit | edit source]

The following Criteria will be used to assess the success of this project. These criteria were chosen based on the suggestions of the project coordinator as well as the diligent students who are working on the catchment system. The scale (1-10) represents the importance level of meeting the constraint of each listed criteria.

Criteria Constraints Weight
Safety Meets or exceeds OSHA standards
Aesthetics Current aesthetic
Maintainability 1 year
Usability 10 foot radius of water usability
Sustainability 100% made up of reused materials
Water Catchment percent 95% caught to overflow
Cost CCAT budget 2018
Community access Anyone can access the water
Lifespan/ durability 5 years durability

Literature Review[edit | edit source]

Rainwater Catchment[edit | edit source]

The Rainwater Catchment system at Cal Poly Humboldt's CCAT house demonstrates how roof space can be used to capture rainwater for cleaning tools, watering plants and other practical uses.It is meant to demonstrate how students can build, design, and implement a system which catches water for the CCAT house. Catchment and storage of water through a rainwater catchment system means not only can CCAT save money on water, but CCAT can make use of water which will naturally fall into the drain for practical uses on the property.

CCAT[edit | edit source]

CCAT has provided HSU students with hands on experience in sustainability since 1978. Through life in laboratories, classes, workshops, and tours CCAT supply its learners with knowledge and methods to live with less environmental impact. The student ran and funded program impressively uses less than five percent of the total energy consumption of the average American home, uses near zero waste, and leads in being one of the most success appropriate technology programs. Students that engage in CCAT’s will learn leadership and technical skills that will serve in expressing their creativity. In closing, CCAT’s goal is to serve the global community as a whole, sustainably. [[1]]

Climate[edit | edit source]

Arcata, California receives 7 inches more than the national average of rainfall annually at 46 inches. Rainfall occurs roughly 20% of the year and has the average temperature of 65 degrees Fahrenheit. Roughly 175 days are considered sunny with a low average temperature of 41 degrees Fahrenheit. Arcata is considered a comfortable climate rating a 79 out of 100 on the Sperling’s comfort index. [[2]]

Storage[edit | edit source]

Storage is usually the most expensive component of a rainwater system and often determines the type of filtration and pumping system. There are a variety of types of rainwater catchment systems available, ranging in quality and durability. The most common storage containers are large-scale plastic tanks, 55gallon barrels, and custom ferrocement tanks. Free-standing plastic tanks provide the least expensive means of rainwater storage, both in purchase cost and installation cost. Always be aware of soil compaction when finding a place for the storage container to be located. A large 1500 gallon rainwater tank was used at the CCAT water catchment system. It is apparent that the container is black. To prevent algae build up.(1)[[3]]

Conveyance[edit | edit source]

The conveyance system of a rainwater catchment is what brings the water from the roof or catchment system into the water storage tank. The parts of conveyance consist of gutters, piping, first flush, screens and filters. For the purpose of this literature review, the piping will be emphasized. Different materials can be used for piping. The inexpensive option of PVC piping will be used for this project. PVC is a very durable plastic that does will not leach or corrode from contact with water. An important aspect of using PVC is the diameter. Wider diameters will cost more, making the smallest diameter possible beneficial to reduce cost.


Screens[edit | edit source]

Once the rainwater runs off of the roof(catchment surface) it is caught in the gutters. We have a flexible pipe installed to catch the water strait from the gutter. Inside this flexible pipe we installed a screen to make sure leaves don't get stuck in the conveyance and dirty the tank. This can easily be pulled out of the gutter for maintenance cleaning.

First Flush[edit | edit source]

Rainwater will pick up the majority of contaminants as it flows across your roof and into your collection tank. A first flush system is a solution to contamination by diverting the first water caught with debris and flushing out contaminants before it reaches your water storage unit. Bacteria mold and algae are the most common contaminants in a rainwater holding system so shaded containers which block sunlight help fight contamination. Closed containers also help avoid contamination by not letting in extra bacteria or mosquitos into the water storage unit.3. First, flush systems allow for less water harvested but cleaner water within the water storage unit. “diverting the first part of the rainstorm can reduce the incoming contamination by 90% while delivering 85% of the water as measured after the storage tank. Greater material removal is possible but with significant loss of water.”4. Two types of first flush methods are the tipping method and the floating ball method. The tipping method allows a bucket to fill with water and spill before filling the water storage unit. The floating ball method allows the first rain to fill the first flush unit until a floating ball closes up the first flush and allows the remaining water into the main water storage unit. A small borehole near the bottom of the first flush allows the first water to slowly drain. A removable cap in the first flush allows for cleaning contaminants compiled within the first flush.

Tank 2757.jpg

Prototyping[edit | edit source]

We held pipes up to where we thought they needed to be height wise and took pictures in order to see where we should install our posts and pipes. We also held up plants near where we thought we would plant the grape vines in order to make sure that is where we wanted to plant them.


Construction[edit | edit source]

How we Constructed: The first step was to deconstruct the current rainwater system. We thoroughly drained and cleaned the catchment tank with Dr. Bronners all natural soap. We took cut, cleaned, and spray painted the old pipes white. We dug holes, mixed concrete and set four 4x4 posts. We then reattached pipe across posts and fastened them with metal fasteners. To reinforce the weight of the grape vines we installed 2x6 boards on either side of the posts alongside the pipe. We turned the tank 180 degrees for better placement of the hose attachment. We cut the concrete in front of the catchment tank in order for better water flow. We also changed the knob on the first flush to one which does not allow for full shut off. We made signs and a laminated instructions book for care, maintenance, use, importance and operation of the rainwater catchment system.

Proposed Budget[edit | edit source]

Some materials will be reused or are available on site such as 3" PVC and wooden signs so they may get taken out of our total cost. We are also proposing a possible rainwater purification system, however we are unsure if client would want it and if a home made system or a store bought system would be better.

Quantity Material Source Cost ($) Total ($)
1 Rainwater Tank Lid 89.99 89.99
1 20 ft. 3" PVC Ace Hardware 15 15
1 15 gallon bucket Ace Hardware 25 25
2 1/8” Screen filter Ace Hardware 2.50 5
1 Hose bib attachment for 15 gallon tank Ace Hardware 18.90 18.90
1 ABS 90 degree elbow Ace Hardware 5.75 5.75
2 60 Lb Dry Cement Mortar MIx Ace Hardware 8 16
5 Grape Vines 6.99 34.95
1 PVC bushing Ace Hardware 1.49 1.49
1 fasteners bolts screws and nuts Ace Hardware 1.69 1.69
2 Quick Release- couplings Ace Hardware 5 10
5 Metal fasteners Ace Hardware 5 5
4 4x4 9 foot Posts Home Depot 43.37 216.85
1 Cleaning Supplies, Rags, Sponges Dollar Store 20 20
3 Wooden Signs Ace Hardware 7 21
1 Paints Ace Hardware 40 40
Total Cost 525.63

Tessa2 2963.jpg

Proposed timeline[edit | edit source]

The following Proposed timeline is a rough outline of the rest of the spring semester, working up until May day, April 28, 2018.

Date Action
3/4/2018 Research purification systems
3/8/2018 Give budget to CCAT for purchase before break
3/21/2018 Assess items purchased and received and received
3/25/2018 Take down old rainwater system
3/27/2018 Clean all reusable materials + tank
4/4/2018 Begin construction. Lay concrete for posts
4/6/2018 Replace conveyance system
4/10/2018 Finish contruction, plant vines and test
4/11/2018 Testing continued

Operation[edit | edit source]

Water from the Rooftop will flow into the gutter and funnel into the pipes. This water then goes through the first flush tank where the dirtiest catch is filtered out and the rest of the water flows into the catchment tank for storage. To operate, you simply turn the hose attachment on at the bottom of the catchment tank. When finished with the water, you turn off the hose and the water will stay stored in the catchment tank for the next use.

Maintenance[edit | edit source]

To maintain the rainwater catchment system cleaning must happen at different periods for different parts.

Schedule[edit | edit source]

Daily - use water from tank

Weekly - check if first flush system is still draining the first catch of water. - if clogged, use the quick release pipe connections to check for debris in first flush tank. - clean out debris if overly clogged.

Monthly - look into the gutter where it attaches to the pipes and check if filter is still intact. - clean out debris if caught in filter. - pull on the green attachment pipe that fits into the gutter. - a micro screen filter is attached within the gutter filter that should be cleaned out in order to not pile up debris.

Yearly - take off 2 by 6 boards and check for leaks on the pipe attachment. - check for leaks on pipe attachments near first flush and the right angle connection. - check that grapes are growing towards their posts. - wrap grape vines in a swirl around their nearest post. - check on grapes and eat them.

Team[edit | edit source]

Nick Rasmussen, Stefan Robles, Katrina Salinas, Tessa Tobar

References[edit | edit source]

1.) Fryer, Julie. The Complete Guide to Water storage: how to use tanks, ponds, and other water storage for household and emergency use. Atlanta Publishing Group Inc. 2012

2.) Grafman, Lonny. To Catch The Rain. Cal Poly Humboldt Press 2017

3.) Martinson D.B, Thomas T.H. Quantifying the First-Flush Phenomenon: Effects of First-Flush on Water Yield and Quality. Department of Civil Engineering, University of Portsmouth, Portland Building, Portland Street, Portsmouth, PO1 3AH, UK. 2009

4.) "RAINWATER STORAGE." Rainwater Harvesting - Storage. Accessed February 18, 2018.

5.) Srinivas, Hari. "An Introduction to Rainwater Harvesting." Accessed February 18, 2018.


7.) [[4]]

Page data
Authors Katrina Salinas, Stefan Robles, Tessa Tobar, nick rasmussen
Published 2018
License CC-BY-SA-4.0
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