Thailand monitors 8 reservoirs despite adequate water supplies
ONWR says national reservoir storage stands at 59% of capacity, with more rain forecast and 8 large reservoirs under watch.
- Thailand's overall water supply is considered adequate, with national reservoirs at 59% of capacity, which is sufficient for the remainder of the dry season.
- Despite the overall stability, the Office of the National Water Resources (ONWR) is closely monitoring 8 specific large reservoirs.
- These 8 reservoirs are under watch because their water volumes have fallen below the benchmark control level, also known as the "Low Water Level".
- In addition to the large reservoirs, 67 medium-sized reservoirs are also being monitored for having water levels below 30% of their capacity.
The Office of the National Water Resources (ONWR) reported Thailand’s overall water situation as of 7am on Sunday (May 3, 2026), saying water volumes in reservoirs nationwide remained sufficient for use until the end of the current dry season.
However, it has announced monitoring for 8 large reservoirs where water volumes are below the benchmark.
Weather forecast: prepare for more rain on May 4-5
For Monday, upper Thailand and the South will still see isolated thunderstorms, but people are advised to prepare for conditions over the coming week.
- Monday-Tuesday (May 4-5): Rainfall is expected to increase in the North, Central, Northeast, and South.
- Wednesday-Friday (May 6-8): Rain in upper Thailand is expected to ease, while the South should remain on alert for heavy rain in some areas.
Reservoir water situation nationwide
Current overall reservoir storage stands at 59% of capacity, or 47,381 million cubic metres, with details by region as follows:
- North: 15,998 million cubic metres (58%)
- Northeast: 5,672 million cubic metres (47%)
- Central region: 660 million cubic metres (34%)
- East: 1,085 million cubic metres (35%)
- West: 19,051 million cubic metres (67%)
- South: 4,915 million cubic metres (63%)
Focus on economic areas and the EEC
The water situation at three main reservoirs in the Eastern Economic Corridor (EEC) continues to be closely monitored:
- Prasae Reservoir: 165 million cubic metres (56%)
- Bang Phra Reservoir: 56 million cubic metres (48%)
- Nong Pla Lai Reservoir: 75 million cubic metres (46%)
Water quality: Bang Pakong River under watch
Checks on water quality for consumption and agriculture found that most areas remained within standard criteria, not exceeding 0.25-2 grammes per litre, except the Bang Pakong River at Bang Taen monitoring station in Prachin Buri, where salinity exceeded the prescribed standard.
Reservoirs under monitoring: water levels below benchmark
ONWR said 8 large reservoirs were under monitoring because their water volumes were below the control level, or Low Water Level:
- North: Mae Mok Reservoir
- Central region: Pa Sak Jolasid Dam
- Northeast: Huai Luang Reservoir
- East: Khun Dan Prakan Chon Dam, Khlong Si Yat Reservoir
- West: Vajiralongkorn Dam, Pran Buri Dam
- South: Bang Lang Dam
In addition, 67 medium-sized reservoirs nationwide have water levels below 30%.
Relevant agencies are managing water resources to ensure sufficient supplies until the end of the 2025/2026 dry season.
