Rainwater Collection and Storage in Thailand: Design, Practices and Operational Issues

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• Rainwater Collection and Storage in Thailand
  Design, Practices and Operational Issues
• C. Visvanathan, J. Kandasamy and S.
  Vigneswaran
• Environmental Engineering and Management Program,
  School of Environment, Resource and Development,
  Asian Institute of Technology, Thailand.
• Faculty of Engineering, University of
  Technology, Sydney (UTS) Australia

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• Rainwater Harvesting
• collection and storage of rainwater for human
  related activities.
• uses simple systems such as jars and pots.
• Rainwater Harvesting is Popular
• decentralized and in proximity to the end user.
• can avoid environmental problems of conventional
  centralized large-scale water supply systems.

3

• Royal Thai Government Rural Water Resources
  Policy (1979)
• focuses on decentralized scheme.
• co-ordination and planning responsibilities
  given to the district.
• managed by local authorities with community
  participation.
• Three Small Scale Technologies Introduced
• jars and tanks for drinking water,
• shallow wells for domestic water and
• small weirs for agriculture.

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• Policy Successfully Implemented
• 1987 - 24 of the rural population was served by
  rainwater harvesting.
• 1990 - census reported the population served by
  rainwater harvesting had increased to 35
  (WHO/UNICEF, 2004).
• 1992 - review by the National Economic and
  Social Development Board (NESDB) showed 8 million
  2 m3 rain jars in use.
• 2005 - rainwater jars remain popular.

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• Typical Rainwater Harvesting System
• Roof Catchment iron sheets, tile, corrugated
  plastic.
• Conveyance System gutters and down pipes.
• Storage in Rain Jars and Tanks.

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• Rain Jars
• Capacity of 1-2 m3.
• Made of mortar mix of cement and sand.
• Easily transportable by pickup truck by two men.
  
• 2 m3 jar costs 250-300 baht (USD 6.5-8).
• Rain jars are the cheapest in comparison to all
  other storage units.

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• Tanks
• Capacity of 6 to 15 m3.
• Bamboo reinforced concrete tanks, rectangular
  or cylindrical.
• Set of three 11m3 tanks for Baht 40,000
  (USD1,000), PDA.
• Design features include secure lid, inlet
  filter, tap, sump and manhole for cleaning.
• Population and Community Development Association
  (PDA)

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• Water Quality Aspects
• Only 2 out of 89 rainwater tanks and none of 97
  rainwater jars sampled contained pathogens.

Wirojanagud et al., 1989
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• Water Quality Aspects
• 40 rainwater jars sampled met WHO drinking
  water standard.

Yes meets standard No does not meet
standard, Wirojanagud et al., 1989
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• Water Quality Aspects
• The heavy metals analyzed included cadmium,
  chromium, lead, copper, iron, magnesium and zinc.
• None of these exceeded WHO standards with the
  exception of magnesium and zinc, which are
  considered to affect only the aesthetic quality
  of rainwater.

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• Water Quality Aspects (continued)
• By comparison rainwater is the safest and most
  economical source of drinking water.
• Improved collection and handling practices
  recommended.
• Boiling, despite limitations, is the easiest and
  surest way to achieve disinfection.
• Chlorination not recommended.
• Photo-oxidation using UV radiation in strong
  sunlight can remove both the coliform and
  streptococci. Use plastic bottles in strong
  sunlight for 5 hrs.

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• Maintenance Issues
• Community rainwater jars suffer from neglect
  particularly those with intermittent use
• Mosquito infestation is a common problem
• Net covers or galvanized covers have not proved
  effective and the screening technique appears to
  be unsuccessful.
• It is important to develop a method of
  preventing mosquito infestation.
• Poor guttering reduces capture

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• Socio-Economic Aspects
• Factors that favored rapid uptake of rain jars
  are
• Demand by communities- poor quality of
  alternative water supplies.- rainwater is clear
  and tastes fresh.- residents need not fetch
  water from a distance.
• Jars have a long history of use in Thailand,
  acceptable to residents and did not clash with
  local culture and practice.
• Local artisans have experience in the manufacture
  of the rain jars.

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• Socio-Economic Aspects (continued)
• The cement and other raw materials are relatively
  cheap.
• Implementation during a period of rising national
  economic growth and private affluence.
• The program was administered and supported by
  indigenous engineers, technicians and
  administrators who easily won the local peoples
  trust.

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• Implementation
• Implemented in all regions of the country by
  government with the active participation of
  individual households, village council and NGOs.
• Role of National Government- initiated and
  fostered the introduction of rainwater jars. -
  subsidised the cost of research for designs and
  construction methods.- training.- construction
  materials.

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• Implementation (continued)
• Users had a key role- Each household were
  directly involved in the provision of their own
  rainwater harvesting and storing system.
• Communal systems planned by village councils.
• Communal system also planned by non-government
  organisations as well as private organizations.

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• Case Study North East Thailand
• Commenced in November 1985.
• Implementation strategy involved villagers -
  financial management.- construction - free
  labour.
• Government support in the form of - training and
  tools. - research and administrative costs.-
  start up loans for village revolving fund (US250
  per village).

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• Case StudyNorth East Thailand (continued)
• Successful - 10 million rainwater jars
  constructed
• Successful because- simple, inexpensive
  technology and understood by users. -
  acceptance/ traditional use of rainwater for
  drinking.- traditional use of earthen vessels
  for rainwater collection.- relatively cheap
  cost of the technology.- easy access to water at
  each house.- poor quality of alternative
  supplies.

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Rainwater Harvesting Australian Practice
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Rainwater Harvesting Statistics Source
Guidance on use of Rainwater Tanks, Australian
Government Dept of Health and Ageing, 2004 ISSN
0642824436
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• Rainwater Tank Rebate - Sydney
• Applies to new tanks with a capacity of 2 m3 or
  more purchased before 31 July 2008
• The rebate is based on the size of the tank and
  whether the rainwater is 'plumbed' into the
  toilet or washing machine.
• Source Sydney Water Corporation (2006)

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• Rainwater Tank RebateSydney Schools
• Refunds the cost of purchasing and installing a
  rainwater tank(s), up to a maximum of 2,500
• Installed before 31 July 2008
• has a minimum total tank capacity of 10 m3 or
  4.5 m3 for schools with less than 300 students
  and if other special conditions apply
• is connected to a fixed irrigation system and/or
  connected for toilet flushing.
• Source Sydney Water Corporation (2006)

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• Rainwater Tanks
• Construction Material
• galvanised steel (Aquaplate, Zincalume) most
  commonly used.
• plastic and fibreglass - suitable where food
  grade standard is required and can prevent light
  entry and algal growth

• concrete strong lasting and can be used
  underground.

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Rainwater Tanks Applicable Standards Australian
Standards that apply to tanks and their
associated fixtures and fittings are ? AS 2070
Plastics materials for food contact use ? AS/NZS
2179 Specifications for rainwater goods,
accessories and fasteners ? AS 2180 Metal
rainwater goods selection and installation ?
AS/NZS 3500 National plumbing and drainage code ?
AS/NZS 4020 Testing of products for use in
contact with drinking water ? AS/NZS 4130
Polyethylene (PE) pipes for pressure applications.
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Rainwater Tanks - Typical Sizes

• Tank size depends on ? the volume of water
  needed? the amount and pattern of rainfall? the
  area of the roof catchment? the security of
  supply required.
• Average indoor consumption is 100-200
  L/person/day
• Average roof area is 100 m2 for a small house and
  200m2 or more for a large house. Communal
  facilities may be larger (600m2)

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Rainwater Tanks - Typical Sizes
1) NA tank size too large for practical
application2) minimum size of tank is 1 m3 2)
assumes 90 security 3) source- Guidance on use
of Rainwater Tanks, Australian Government Dept
of Health and Ageing, 2004 ISSN 0642824436
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