Integrate water resources management are necessary in Thailand. The only use of
ground water now can cause subsidence of land. In Ayuthaya, ground water is major
source of water supply. It is also use as source of drinking water. Based on its quality,
cost of treated ground water is much higher than rainwater. Thus, rainwater could be high
potential as alternate resource for drinking water.
Similar to other regions in Thailand, rainwater has been an important source for
domestic water supply for both non-potable and potable use in the study area of Bangsaiy
Municipality for a long period of time. Being located in Ayutthaya where the average
annual rainfall is 1,347 mm and although not as high as other regions such as the southern
part of Thailand, if harvested, the rainfall in the municipality is sufficient for portable use
particularly drinking and cooking throughout the year and for other domestic purposes
during the long rainy season. Although the quality of rainwater has been of much concern
to the local residents due to increased pollution in the environment, in accordance with
past studies and research, chemical parameters particularly heavy metals still meet the
drinking water standards. High biological contaminants which mainly come from
flushing rooftops when rainwater is harvested at the beginning of the rainfall can be
alleviated by improving rainwater collection methods, installing simple treatment
systems such as first flush devices and hygienic handling of rainwater. According to the
questionnaire survey and field observation, approximately, one third of households have
rainwater conveyance and storage facilities in place, although some of their facilities are
not in good conditions. Based on supply side considerations, there is no doubt, there is a
high potential in rainwater harvesting in small urban areas like Bangsaiy Municipality.
A pilot project must be designed in a way that can prevent these contaminants from
polluting the harvested rainwater. Apart from designing a pilot project to meet the user
demands, educating water users to realize the benefits to be gained from rainwater
harvesting pilot project is very important. Community education should be conducted to
make them appreciate the quality of rainwater.
The example of appropriate design are shown in the estimate cost about 50,000 to
80,000 THB.