Contributors

Team BGRZ is made up of four Cal Poly Humboldt students and alumni: Brianna Diaz, Gabriela Pecina Escobar, Robert Duncan and Zach Estela. Brianna is an Art Education/Spanish major. Gabriela is a Spanish Education major. Robert has graduated with a B.S. in NRPI (Natural Resources Planning Interpretation). Zach has graduated with a B.S. in Environmental Science - Appropriate Technology and Climate Change. Project partners are as follows:

• Otros Mundos
• Juan Hidalgo, earthen builder and owner of an appropriate technology demonstration house in San Cristobal
• Indigenous community members

Weighted Table

This table defines and weights the criteria used to evaluate a successful project.

Reasons For Contamination

Four main reasons for rainwater contamination are as follows:

1. Polluted while passing through atmosphere
2. Filth collected during dry season
3. Dirty roof, e.g. animal or bird droppings
4. Pollution through collection unit^[2]

Materials

System Design

There are many designs for rainwater catchment systems. The designs vary because of several factors:

• Roof type, shape and size
• Tank type, shape and size
• Purpose of water, ex: garden or drinking?
• Materials used (budget)
• Space to put tank
• Where is tank in relation to roof
• safety: Will there be kids around? Animals? Is it in a walkway?

=== Making Rainwater Safe to Drink ===^[6]

Rainwater must be kept free of contamination to be safe to drink. To support that water you collect will be safe:

• Clean the tank, entrance pipe, and roof gutters before the rainy season.
• Allow the first rains of each year to run through the tank to clean it.
• Connect a water filter to the tank (slow sand filter is a simple way to do this).
• Porous beds are part of sand-gravel filters used to clean rainwater. This article has a great photo of a porous bed.
• Animated video http://www.youtube.com/watch?v=YaOOmaGzx0g

• First flush systems are very simple filtration systems to get out larger debris before the sand filter. This helps to keep maintenance to a minimum.
• The tipping gutter system works by filling up a bucket with dirty water, when bucket weighs enough it will change the direction of the gutter to fill up the storage tank.
• The floating ball technique functions by having the contaminated water fill up a pipe that has a ball in it. The ball floats to the top as the pipe is fill and eventually seals the pipe so the clean water is diverted to the water harvesting tank.^[7]

floating ball demo

Climate Data for San Cristóbal

Rainfall Data for Mexico

This table shows rainfall data for the 10 rainiest states of Mexico in millimeters both by monthly averages and yearly totals

Temperature Data

This table shows monthly temperature and rainfall data for San Cristóbal, as well as annual averages and totals

Equations

See Basic rainwater collection calculations for relevant rainwater collections equations and a rainwater calculation spreadsheet.

Juan Hidalgo's demonstration house

Day 1-2:

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  Fig. 1: Tank area before hole was dug
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  Fig. 2: Zach digging the hole
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  Fig. 3: Robert and Zach working hard
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  Fig. 4: Shovel in the hole
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  Fig. 5: Robert tamping dirt
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  Fig. 6: Bri tamping costals
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  Fig. 7: Zach and Juanito checking the level of the tamped area for tank
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  Fig. 8: Gabby and Brianna making a poster for the community

Day 3:

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  Fig. 1b Gabby digging holes for beams
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  Fig. 2b: Brianna and Zach filling holes with sand to secure the wood beams in place
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  Fig. 3b: Zack and Robert nailing the gutter to the wood beams
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  Fig.4b: Cutting PVC to length

Day 4:

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  Fig. 1c: Robert drilling hole for mesh bottle
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  Fig. 2c: The bottle fits!
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  Fig. 3c: Bri hammering brace together
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  Fig. 4c: Hammering brace to wall

Day 5:

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  Fig. 1d: Robert hammering, happy helper painting motor oil on wood, Zach checking level of pipe
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  Fig. 2d: Robert cleaning the tank
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  Fig. 3d: Bri sealing water bottle with caulk
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  Fig. 4d: First flush system all set up
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  Fig. 5d: After we cut down the first system
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  Fig. 6d: Cut down piece
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  Fig. 7d: New first flush
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  Fig. 8d: Flap to divert water
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  Fid. 9d: Connect to rest of system
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  Fig. 10d: System 2 completed

Our steps of installation:

1. Dug through the meter or so of saw dust that was covering the ground to reach solid earth. We needed a solid foundation for the ton or so of water that would eventually fill the tank.
2. Filled the hole with Costales (sacks) of dirt and tamped them down to create a strong and level foundation. Using a level, we added dirt and sand on top of the sacks to ensure that it was even.
3. Moved the 1100 liter Rotoplas tank to its location and put palate underneath to boost it up a few inches. This ensures easier access to the drain spout for future users.
4. Set up gutter system. This involved digging holes for wood support beams, cutting the wood to length, installing the three beams, filling the holes with sand and tamping firmly.
5. Next came cutting the galvanized corrugated roofing metal (known in mexico as lamina) with an angle grinder with cut-off wheel, bending the lamina intocutting and wrapping wire to the gutter to hold the shape, attaching the gutter to the roof and beams using nails and wire
6. Made a table for the first flush system to support its weight when it is full of water.
7. Constructed a platform for the mesh wrapped bucket to sit on and hammering holes in the bucket so we could secure the mesh screen to it
8. Realized the first flush system was too high so we lowered it about 10 inches
9. Patched some holes in a gutter (we had used a scrap piece of galvanized sheet metal which had holes)
10. Cut PVC to length and attached together
11. Cleaned tank and cut hole in the lid so that a 3" PVC pipe could fit in
12. Connected the tank to the rest of the system
13. Conducted a test we found out we had some leaks so we sealed the leaks with silicon caulk
14. Conducted more testing and realized the water bottle would not seal to the PVC so we tore down that system and created a new one

Steps of re-installation:

1. Measure from water bottle to one foot above ground
2. Cut pipe
3. Put together first flush system
4. Connected first flush to mesh screen filter
5. Tested before connected to rest of system and discovered water going to both first flush and tank
6. Created flap to divert water
7. Connected rest of system to tank
8. Tested successfully

Testing: Demo House

Test 1: Checking the position of the mesh covered bucket

Test 2: Checking the system to see how it works

Test 1: New design:

Systems at Community

System #1

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  Fig. 1e: Cutting the metal for the gutters
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  Fig. 2e: Unshaped gutters
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  Fig. 3e: Zach and Robert shaping gutters
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  Fig. 4e: Gabby and Bri prepping gutters for wiring
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  Fig. 5e: Bri prepping bucket for mesh
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  Fig. 6e: Completed mesh
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  Fig. 7e: Wood supports for gutters
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  Fig. 8e: Robert attaching first gutter
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  Fig. 9e: Attached gutters
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  Fig. 10e: View of gutters
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  Fig. 11e: Testing gutters
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  Fig. 12e: Gutters fail test
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  Fig. 13e: Zach adjusting gutters
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  Fig. 14e: Gutters pass second test

System #2

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  Fig. 1f: Zach recylcing wood for the supports
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  Fig. 2f: Wood supports
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  Fig. 3f: Shaped & wired gutters
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  Fig. 4f: Testing Side A of roof
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  Fig. 5f: Side B of roof
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  Fig. 6f: Gutters, side B
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  Fig. 7f: The PVC tubing that connects the two gutters and feeds underground to the first flush and tank
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  Fig. 8f: Carrie and Max mounting the bucket filters
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  Fig. 9f: Carrie Schaden burying the tank bound pipe to allow a footpath
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  Fig. 10f: 19,000 liter ferrocement tank being constructed.
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  Fig. 11f: 19,000 liter ferrocement tank filled with water.