5.5 Rainwater harvesting - the Thai rainwater jar

Introduction

Thailand's National Jar Programme, to supply of clean drinking water to rural areas, was launched in response to the United Nations' Water Supply and Sanitation Decade (1981-1990). The Program's objective was to promote the use of jars in rural households as a means of supplying clean drinking water. User participation was encouraged, although, early in the program, rural poverty was endemic and villagers could only provide in-kind labour. Government subsidized the cost of research (to find suitable designs and construction techniques), training, and construction materials. Some jars were provided without cost in cases of extreme need, although this was not the intent of the Program. While private sector involvement in the Programme was not planned in the initial project design, commercial production of rainwater jars eventually replaced the Government-subsidized jars, to the benefit of everyone concerned. Such privatisation continues, and Government, now, is no longer involved in jar production.

As the name implies, the Programme was national. It covered all regions of Thailand, including the south which receives rainfall almost throughout the year. Not surprisingly, however, rainfall jars are not as widely used in the south as in other regions. Culturally, the jars are not new to Thailand, and, hence, are well-accepted by users. Small-sized jars (0.5 m³) have been used in households for generations without Government intervention. However, the National Jar Programme promoted the use of large jars (2 m³) as the most cost effective size. In line with traditional practice, the 2 m³ jars were designed to be household-oriented.

Technical Description

Jar construction techniques are similar to ferrocement tank construction techniques. The shape of the jar resembles a sphere, thus offering the most efficient use of materials in term of strength per unit of mass. An empty 2 m³ jar is transportable, and can be hauled onto a pickup truck by two men using simple, locally available equipment. The construction technique is simple and compatible with locally available skills. The technology has performed well as evidenced by its acceptance by the private sector; commercial jar manufacturers can be seen along highways throughout the country. Most rural households now have at least two jars, the service life of which is estimated to be 20 years.

Extent of Use

Before the technology was introduced, research was conducted to find the optimum size and most suitable construction technique for the jars. Their introduction was undertaken through various Government-supported, village jar construction projects, and the King's 60th birthday (5 December 1988) was used as a milestone for targeting achievement. Mass media played an important role in publicizing and promoting the use of the rainwater jars. The project was subject to some initial skepticism from the mass media and some public figures, but this was silenced by widespread acceptance of the jars by rural households. There was also some corruption involving the Government funds provided for village jar construction, which resulted in the production of some substandard jars. Leakage and breakage were common in such cases. However, shifting of manufacture of the jars from Government programmes to the private sector eliminated this corruption.

Operation and Maintenance

Similar to most household-oriented commodities, such as televisions and appliances, rainwater jars are operated and maintained by their owners. The producers of the jars (formerly Government and currently commercial jar manufacturers) have no role beyond the initial sale of the product. Operation and maintenance problems include personal injuries sustained during cleaning, breakage of the jars due to accidents, and contamination resulting from animals licking the discharge taps, using unsuitable roofing and guttering materials, or neglecting to use the jar lids.

Level of Involvement

Table 32 presents a summary of the levels of involvement by parties concerned with the production, promotion, installation and operation of rainwater jars.

TABLE 32. Summary of Roles and Responsibilities of Parties Involved in Rainwater Jar Implementation.

Costs

The capital costs of a rainwater jar are summarized in Table 33. Based upon this figure, the average cost of water supplied using this technology is $1.10/m³/year.

TABLE 33. Capital Cost of a 2 m³ Rainwater Jar

The operation and maintenance costs of a rainwater jar are summarized in Table 34. The costs are estimated based upon the annual cost of operating and maintaining two rainwater jars, with the labour costs estimated at the Government's basic minimum wage of $0.65/hr.

TABLE 34. Operation and Maintenance Cost of a 2 m³ Rainwater Jar.

Including both the capital and operation and maintenance costs, then, a typical household will spend $8.50/m³/year for clean drinking water using jars. The alternative source of drinking water is bottled water, popular in urban areas, which may be purchased at a cost of about $0.65/litre, or $645.00/m³ - more than 75 times more expensive than jar water. This cost differential may be another reason for the jars' popularity. Unlike the rainwater jars, the plastic containers used for bottled water are now causing serious environmental pollution.

Effectiveness of the Technology

According to a 1992 review by the National Economic and Social Development Board (NESDB), the numbers of 2 m³ jars in use in Thailand increased from virtually none in 1985 to nearly 8 million in 1992. This increase was partially due to the Government's National Jar Programme, but mostly due to the willing adoption of the technology but the public and to the widespread promotion of the technology by the commercial sector. Government intervention is no longer necessary.

Surprisingly, in the second half of the UN Water Supply and Sanitation Decade, the sanitation index, compiled from data on public health problems such as the frequency of incidences of diarrhea, increased despite the introduction of the jars and the wider availability of clean drinking water. The success of the National Jar Programme prompted the Government to introduce a similar national programme to improve sanitation, the National Latrine Programme.

Advantages

Local politicians liked the Government's Jar Programme and used the jars as banners for political campaigning, although the jars are no longer connected to politics. The implementation of this technology is totally regulated by economics and free-market mechanisms due to widespread private sector involvement.

Technically, jars have many advantages, including preventing the negative impacts of mosquitoes, which can breed in open water storages and other areas of standing water. The jars also cool households to a certain extent, and there is no longer the need for users to spend time and effort fetching water from beyond the household perimeter. Jars also reduce soil erosion as they intercept rainwater, running off the roof, before it reaches the ground.

Disadvantages

Disadvantages of this technology include the space taken up by jars within households. The jars may also become breeding places for mosquitoes if the containers are not kept closed. In space conscious households, a rainwater tank is preferred over the jars. (Rainwater tanks are a similar technology to the jars except that the tanks are taller and unmovable.) Corruption in the jar programme was endemic at the time the 2 m³ jars were introduced.

Further Development of the Technology

Rainwater jars are successful in the rural areas of Thailand because the technology is simple, inexpensive and understandable to a majority of the rural population. However, this success depended on user and private sector involvement. Success also depends upon other factors; rainwater jars are not suitable everywhere. For rainwater jars to be successful there must be sufficient rainfall distributed throughout the year. Roofing materials are also important considerations as they can negatively affect the quality of water collected. The jars themselves must be transportable without breakage from the manufacturing sites to the consumers. For this reason, ferrocement jars were found to offer advantages in terms of both robustness and mass; however, if cement is expensive, use of rainwater jars may not be feasible. The optimum size of the jars is also dependent on the above considerations. Finally, the potential environmental impacts arising from rainwater jar use must be assessed to avoid solving one (water supply) problem but creating another (public health) problem. To this end, user information campaigns should be undertaken to alert users to the dangers of spreading malaria and dengue fever through the improper use of jars.

Information Sources

Contacts

Dr. Sacha Sethaputra, Associate Professor, Water Resources and Environment Institute, Faculty of Engineering, Khon Kaen University, Tel./fax: 043 241 202; E-mail: [email protected].

Dr. Sanguan Patamatamkul Associate Professor, Water Resources and Environment Institute, Faculty of Engineering, Khon Kaen University, Tel./fax: 043 241 202; E-mail: [email protected].

Mr. Junlajit Sawaengphet, Researcher, Water Resources and Environment Institute, Faculty of Engineering, Khon Kaen University, Tel./fax: 043 241 202; E-mail: [email protected].

Dr. Nalinee Tuntuwanit, Researcher, Research and Development Institute, Khon Kaen University, Tel. 043 244 506, 238 383, fax: 043 244 418.

Ms. Tongtip S., Researcher, Research and Development Institute, Khon Kaen University, Tel. 043 244 506, 238 383, fax: 043 244 418.

Ms. Pacharin L., Researcher, Research and Development Institute, Khon Kaen University, Tel. 043 244 506, 238 383, fax: 043 244 418.

Ms. Sinee Chuangcham, Researcher, Research and Development Institute, Khon Kaen University, Tel. 043 244 506, 238 383, fax: 043 244 418.

Bibliography

Department of Health s.d. Manual for Caretakers of Village Pipe Water Supply Systems (Medium and Small Sizes). Rural Water Supply Division, Department of Health, Bangkok, Thailand 2535.

Department of Health s.d. Manual for Caretakers of Village Pipe Water Supply Systems. Rural Water Supply Division, Department of Health, Bangkok, Thailand 2535.

Department of Local Administration 1987. People's Volunteer Weir Program for Small Water Resources Development. Ministry of Interior, Bangkok, Thailand.

NESDB [National Economic and Social Development Board] 1992. Manual for Preparation of Master Plan for Provision of Drinking and Domestic Water for Villages in Each Province, NESDB, Bangkok, Thailand.

NESDB [National Economic and Social Development Board] 1992. Status of Drinking and Domestic Water in Rural Areas. NESDB Division of Rural Development Coordination, Bangkok, Thailand.

Office of Public Health s.d. Manual for Management of Village Pipe Water Supply Systems. Sanitary and Environmental Health Division, Office of Public Health, Chiangrai, Thailand 2535.

Thongtip, S., L. Pacharin, and K. Wichien 1995. Esan Women and Water Management, Research and Development Institute, Khon Kaen University, Thailand (in Thai).

Water Resources and Environment Institute 1986. Manual of Weir Construction. The KKU-NZ Weir Project Report, Khon Kaen University, Thailand (in Thai; English, Laos and Cambodian translations available).

Water Resources and Environment Institute 1991. Small Scale Water Resources: Clean Water and Sanitation. Thai- German Self-Help Training Project Report, Khon Kaen University, Thailand (in Thai).

Water Resources and Environment Institute 1991. Manual of Small Weir Design. Thai-NZ Small Watershed Development Project Report, Khon Kaen University, Thailand (in Thai).

Water Resources and Environment Institute 1991. Manual for Construction of Farm Pond. That-German Self-Help Training Project Report, Khon Kaen University, Thailand (in Thai).

Water Resources and Environment Institute 1991. Manual for Construction of Impact Well. Thai-German Self-Help Training Project Report, Khon Kaen University, Thailand (in Thai).