Thailand's Water Supply
Sufficient freshwater availability is a critical factor for Thailand's future development. Water is required for domestic consumption, for agriculture, for tourism, for industry and energy production, as well as environmental preservation. These various demands compete for the water resources which are available, and require careful management to ensure all are fairly provided for. At present, a combination of industrial growth, population growth and rising incomes has led to increases in the demand for water, estimated to be growing at about 20 percent a year
Nationwide, potable water supplies are generally provided by two agencies: the Metropolitan Waterworks Authority (MWA) and the Provincial Waterworks Authority (PWA). The MWA is responsible for the production and distribution of potable water in the Bangkok metropolitan region, while the PWA is responsible for water source development, treatment, storage, and distribution to all the urban and rural communities in the provinces.
Thailand's current overall development strategy is to continue to improve the country's water supply infrastructure services nationwide by improving and expanding existing reservoirs, swamps, weirs, and natural water resources; particularly in the Northeastern provincial clusters served by the Loei, Chi, and Mun river basins, which are key cultivation bases for the major economic crops of the region. Additionally, Thailand seeks to reduce the volume of non-revenue water in the country's water transmission and distribution systems, and to establish an integrated management system for water supply operations. A major goal is to provide all households in the Bangkok Metropolitan Region with water supply services by the end of 2018, and 100% of all villages and greater than 80% of provincial households prior to the end of 2021.
Climate and Rainfall
Thailand's tropical climate features three main seasons, a dry season from February to May, a rainy season from May to October, and a winter season from October to February. This creates a situation where there can be an excess of rainfall and runoff at one time of year, particularly August and September, followed by drought conditions in at least part of the country during February or March. The annual average rainfall in most of the country is about 1200 – 1600 mm/yr, and which is distributed over approximately seven river basins, which can be further divided into 25 subbasins.
In order to retain the runoff from rainfall during the rainy season, as well as prevent flooding, and prevent a drought situation that could negatively impact the agricultural sector during the dry season, the Thai government has constructed over 3000 dams. Five of these are large capacity dams with capacities of over 5,000 m3 each, Srinagarind at 17.75 km3,Bhumipol at 13.46 km3, Sirikit at 9.51 km3, Vaijiralongkorn at 8.86 km3, and Rat Cha Prapa a6 5.64 km3. These dams are multipurpose in that they also serve as source of hydroelectric power.
Metropolitan Water Services
Serving some 10 million inhabitants in the provinces of Bangkok, Nonthaburi and Samut Prakarn, in 2019 the MWA had an annual water production capacity of about 2,075 million cubic meters, a 4% increase from the previous year. Water supplies were sourced from the Chao Phraya River (70% from the Bhumibol and Sirikit dams), and 30% from the Mae Klong Dam. Also according to the MWA, annual water sales were 1,467.4 million cu meters in 2019, or 70.7% of the total amount available. Historically, MWA has been able to deliver and sell over 75% of its production volume, so there is still a significant unused capacity available as demand continues to grow.
The MWA has remained committed to enhancing all aspects of ongoing water supply operations. There are pipe replacement projects to support an increase in water pressure by up to 10 meters to reduce electricity costs in water pumping and moderating water loss down to 20%, thus strengthening the stability of the production system.
Sources: Metropolitan Waterworks Authority, NESDB and PWA Annual Report 2019, Thai Meteorological Department Last updated: 16 July 2020
