Background

The Practivistas Domincana Program is currently a program involving Humboldt State University and UNIBE that takes place in Santo Domingo, Domincan Republic. The rainwater catchment system in La Yuca in Santo Domingo was first constructed in 2011. The water from this system was used for washing but was not potable. In 2012 the system was reconstructed and had different filters added in order to make the water potable. In the beginning of the summer of 2013, the water is still being used for washing but the water available for drinking is not being filtered, and therefore, it is not being used.

Objective

During the 2013 Practivistas Dominicana Program the objective is to make the La Yuca rainwater catchment system potable as well as easily accessible.

Literature Review

The following information was used to review and learn what is necessary to understand the concepts of design and implementation of rainwater catchment systems in the Dominican Republic.

Rainwater Catchment System

A rainwater catchment system is a system that collects, filters, and stores rainwater for community or household use. [1]

Roof Types

The type of construction material is important for a rainwater catchment system. Depending on what material is used for the roof, the collected water can be contaminated by carcinogens[1]. The roofing materials used in a rainwater catchment system should be chemically inert to keep contaminants out of the system. These materials include aluminum, fiberglass, plastic, and wood [2]. In addition to the roof material itself, the climate can influence the contaminate runoff depending on the material.

Metal roofs are commonly used for their smooth texture, Galvalume (55% aluminum, 45% zinc alloy coated sheet steel) is commonly used and can be treated with epoxy paint or a baked enamel coating. Clay and concrete materials are available for potable systems, clay and concrete are porous, however, which can lead to water loss, evaporation, and bacterial growth. Composite shingles should not be used for potable catchment systems due to the leaching toxins, in addition, wood shingles, tar and gravel are also know for leaching compounds and are therefore unsuitable. The most ideal roofing material for rainwater catchment is slate because of its smooth texture and lack of toxins. The cost of slate can be very high [3]. Various roof paints for roofs are suggested by the National Science Foundation to prevent leaching of carcinogens into the rainwater [4].

Water Treatment Techniques

Water from a rainwater catchment system must be treated before it is considered potable. Techniques for cleaning water vary depending on what filters are available and the contaminants involved. "No one piece of treatment manages all contaminants"[5].

Treatment Result
Screening
Leaf screens and strainers prevents leaves and other debris from entering the tank
Settling
Sedimentation settles out particulate matter
Activated charcoal removes chlorine
Filtering
Roof washer eliminates suspended material
In-line/multi-cartridge sieves sediment
Activated charcol removes chlorine, improves taste
Microbiological treatment/Disinfection
Boiling/distilling kills microorganisms
Chemical treatments(chlorine or iodine) kills microorganisms
Ultraviolet light kills microorganisms
Ozonation kills microorganisms
Nanofiltration removes molecules
Reverse osmosis removes ions(contaminants and microorgaisms)
Treatment techniques[3]

Water Quality

There are three criteria to having acceptable quality drinking water.

  • No fecal bacteria
  • No harmful chemicals
  • No bad taste or smell

Rainwater catchment systems have commonly found contaminants due to the location and isolation of rooftops.

Common contaminants of rainwater catchment systems[6]
Contaminant Source Risk of entering Rain Tank
Dust and Ash Surrounding dirt and vegetation
Volcanic activity
Moderate:Can be minimized by regular roof and gutter maintenance and use of a first-flush device
Pathogenic Bacteria Bird and other animal droppings on roof, attached to dust Moderate:Bacteria may be attached to dust or in animal droppings falling on the roof. Can be minimized by use of a first-flush device and good roof and tank maintenance.
Heavy metals Dust, particularly in urban and industrialized areas, roof materials Low:Unless downwind of industrial activity such as a metal smelter and/or rainfall is very acidic (this may occur in volcanic islands)
Other inorganic
Contaminants(e.g. salt from seaspray)
Seaspray, certain industrial discharges to air, use of unsuitable tank and/or roof materials Low:Unless very close to the ocean or downwind of large-scale industrial activity
Mosquito Larvae Mosquitos laying eggs in guttering and/or tank Moderate:If tank inlet is screened and there are no gaps, risks can be minimized.

The Dominican Republic has the similar water quality standards as the World Health Organization (WHO).

Translated water quality standards for the Dominican Republic [7]
Parameter
(mg/L)
Surface Tension Agents
0.0
Chlorides
250
Chlorine
0.00
Copper, Cu
1.0
Iron, Fe
0.3
Magnesium, Mg
150
Manganese, Mn
0.05
Calcium, Ca
75
Phenol compounds such as phenol
0
Sulfates, SO4
250
Zinc, Zn
5
Total Dissolved Solids
500
pH
6.5<X<8.5

[8] [9] [10]

First Flush

The first flush in a rainwater catchment system is used to clear the roof of debris and airborne residue before it can reach the storage container. The gutter and leaf screen can keep larger debris out of the first flush[3]. Generally the first flush is meant to catch the first 10 min of rainfall, as that is a difficult volume to quantify one suggestion is to divert at least 10 gallons for every 1000 square feet of roof area, an Australian vendor suggests between 13 and 49 gallons per 1000 square feet of catchment surface. The two kinds of first flush diverters include just using a a PVC standpipe, when the standpipe fills the rainwater is diverted to the storage tank. The second kind is a the ball valve, a flouting ball within the PVC pipe shuts seals off the first flush volume and diverts the water.[11][6]

Maintenance

Rainwater catchment systems require consistent upkeep in order to reduce the amount of contaminants.
Every Rainwfall

  • First flush must be completely drained and cleaned

Every Month

  • Primary screen the gutters and any gutter screens must be check for damage or clogging

Every Year

  • Tinaco (or storage tank) must be emptied of sediment and disinfected
  • Sediment and Carbon filters must be replaced

[12]

Climate

The Climate in Santo Domingo is tropical, with year round high humidity, warm temperatures, and varying rainfall. Santo Domingo receives an annual average rainfall of 57 inches. During the wet season (May - October) Santo Domingo receives between 5.5-7.4 in of precipitation monthly. During the "dry" season there are 2.1-3.9 inches of monthly precipitation. The annual temperature remains relatively constant year round, ranging from 24.4-27.1 °C [13]

Criteria

Criteria Constraints Weight
(1-10)
Accessibility
Convenient location for everything
8
Level of Maintenance
Necessary < 3X a year
8
Water Demand
enough for 1 shower per day
5- depends on rain
Educational
at least 1 person
7
Safety
Must be safe for people to enter yurt
9
Time
finish project before we leave
10
Materials
Materials are all local
8
Cost
as inexpensive as safely possible
8
Durability
Long lasting design
7

Final Design

Piping along the wall to the filters
Finished filtration system
Direct faucet into the cistern
Piping from the filters to the bathroom
Bathroom sink
Bathroom showerhead
Sink drains greywater into toilet basin

The director of the school in La Yuca wanted to have potable water in the bathroom and a direct faucet to the cistern. Taking into consideration the director's desires, the final design was constructed to have potable water in the shower sink and greywater use for the toilet.

Maintenance

This final design requires consistent upkeep in order to reduce the amount of contaminants.
Every Rainfall

  • First Flush should be completely drained and cleaned

Every Month

  • Primary screening must be checked for damage or clogging

Every Year

  • Tinaco (or storage tank) must be emptied of sediment and disinfected
  • Sediment and Carbon filters must be replaced

Maintenance Video

Budget

Material Quantity Material Cost (DOP) Total Cost (DOP)

Timeline

June 10th 2013

  • Discussed plan of action

-Find water testing kits -Discuss what is wrong with the current configuration -Figure out questions to ask Aswaldo (Disassemble? Maintenance?)

  • Found out UNIBE does not have any water testing kits.
  • UNIBE normally has a professor take water samples to USAD (809)535-8273
  • An alternative location for water testing is CAASD

June 11th 2013

  • Email with contact information of USAD water lab was recived.
For water quality analysis/PARA ANALISIS DE CALIDAD DEL AGUA

Instituto de: Química de Microbiología y Parasitología UASD.
Director Marcos Dipré 809-535-8273 Ext. 3058
Dr. Modesto. 809-535-8273 Ext. 3066, 67, 68. Cel. 809-449-4306

OR

PURADOM Ave. 27 de Febrero #260 Apto. 203 Edif. Brigite II,
Casi esq. Lincoln,
Santo Domingo, D.N. 10107 Rep. Dominicana
Apartado 4712,Santo Domingo, D.N. 10100
Republica Dominicana
ventas@puradom.com
809-565-9599
Puradom website

  • Checked the hardware store next to super national for first flush ideas and paint. The correct paint was not found

June 12th 2013

  • Went to PURADOM (water filter store, 27 de Febrero and Lincoln) to drop off water samples
  • Results should be ready June 14 or 15.
  • Inspected the entirety of the system
  • Disassembled and cleaned each component

June 13th 2013

  • The hardware store next to Super National does not have any 3 or 4 inch quick releases.
  • They do have 4 inch pipe that they can cut to size.

June 14th 2013

  • Finished cleaning the Tinaco
  • Talk with the director and set up a meeting for Monday June 17th at 4 PM.

June 15th 2013

  • Bought supplies for the first flush
  • Started first flush assembly

June 16th 2013

  • Continued working on first flush
The current condition of first screening
Simone helped us clean out the Tinaco

June 17th 2013

  • Finish putting together first flush, discuss designs, research filters and water pressure and solar pumps
  • Found out that the test results for the current filtration system showed to be not potable
  • Talked with the Director and found out she wants water in the bathroom so she can shower

June 18th 2013

  • Begin purchasing materials for bottom portion of first flush

June 19th 2013

  • Attached first flush to column
  • Discussed piping for bottom portion
  • Found flow rate of original system to be 1.18 gallons per minute

June 20th 2013

  • Complete bottom portion of first flush

June 21st 2013

  • Buy materials for piping to the filtration system

June 22nd 2013

  • Drill hole in wall for PVC to go through
  • Construct and glue PVC along back wall
  • Start working on filtration system

June 23rd 2013

  • Continued to construct filtration system

June 24th 2013

  • After discussing with local helpers, the filtration system was disassembled and rebuilt

June 25th 2013

  • After listening to advice from Puradom professionals, more filters were optained in order to have two parallel series of two filters for more flow to pass through the system
  • More hole drilling to support filters

June 26th 2013

  • Bought more supplies to transport water from the filtration to the bathroom
  • Bracketed pipe for the system

June 27th 2013

  • Completed piping to and in the bathroom, including shower head and sink

June 28th 2013

Went to Las Malvinas to look at the school rainwater catchment system. Ended up with an alternative project to fix the rainwater catchment system in the Play.

June 29th 2013

  • Bought materials for the rainwater catchment system in the Play in Las Malvinas.
  • Fixed the toilet/sink system, and first flush. The first screening still has to be modified.

June 30th 2013

Started Construction on the Play rainwater catchment system.

  • Removed roof
  • Fixed bent sections of the roof
  • Disassembled the rainwater catchment system
  • Cleaned the tinaco

July 1st 2013

  • Finishing touches on the filtration system in La Yuca
  • Water sample was brought to Puradom to see if the water is potable

July 2nd 2013

  • Repaired leak in filtration system

July 3rd 2013

  • Worked on constructing the roof in Las Malvinas
  • Worked on completing powerpoint for our project presentation
  • Received results from Puradom of the current water qualtity. Test results indicated that the water was not potable.

Reasons for water quality failure are as follows
-Not enough bleach was added to the system
-The bleach was not allowed to sit in the water for 4-5 hours before we tested for water quality
-We did not wait long enough for contaminated water to clear and the bleach water to come through
-Due to limited amounts of water, the cleaning and testing process was rushed

July 4th 2013

  • Presentation on our projects

July 5th 2013

  • Finished constructing roof for Las Malvinas

July 6th 2013

La Yuca

  • Attempted to make videos
  • Assisted another group to finish their project

Las Malvinas

  • Installed the PVC gutters
  • Drilled a hole into the cap of the tinaco for the PVC inlet
  • Created the primary screening
  • Finished constructing and gluing the first flush

July 7th 2013

  • Completed Las Malvinas project with the addition of a faucet and adding silicone to a leak.

July 8th 2013

  • Took video of La Yuca project
  • Finished primary screening and with it the project in La Yuca

References

Template:Reflist

  1. 1.0 1.1 Palau Catchment Manual http://ag.arizona.edu/region9wq/pdf/Palau_catchmentmanual.pdf
  2. Rainwater harvesting from rooftop catchments http://www.oas.org/dsd/publications/Unit/oea59e/ch10.htm
  3. 3.0 3.1 3.2 Texas water harvesting manual http://www.twdb.state.tx.us/publications/reports/rainwaterharvestingmanual_3rdedition.pdf
  4. National Science Foundation approved list of paints http://www.nsf.org/Certified/Protocols/Listings.asp?TradeName=&Standard=P151
  5. University of Nebraska, Drinking Water Treatment: Sediment Filtration http://www.ianrpubs.unl.edu/live/g1492/build/g1492.pdf
  6. 6.0 6.1 WATER QUALITY OF RAINWATER HARVESTING SYSTEMS http://www.pacificwater.org/userfiles/file/MR0579.pdf
  7. ANTEPROYECTO II NORDOM 64 (3ra. Rev.)http://www.indocal.gob.do/LinkClick.aspx?fileticket=tLwTVMJm7oY%3D&tabid=114&mid=578
  8. WHO World Health Organization Water Quality PDF http://www.who.int/water_sanitation_health/dwq/gdwq0506.pdf
  9. Dominican Republic water quality http://www.temasactuales.com/laws_policies/legislation_Dominican%20Repub.html
  10. Guide to workplace use of non-potable water http://www.deir.qld.gov.au/workplace/resources/pdfs/non-potable_guide.pdf
  11. First Screening video example http://www.youtube.com/watch?v=mkeBlECXETQ&feature=endscreen
  12. Rainwater catchment maintenance manual http://www.bakerinstitute.org/programs/energy-forum/publications/lesotho/Rainwater%20Harvesting%20Construction%20Manual%20-%20Maintenance%20-%20ENGLISH.pdf
  13. World Meteorological Organization http://worldweather.wmo.int/132/c00281.htm
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