Thailand is monitoring six major reservoirs where water levels have fallen below the minimum control level, though authorities say supplies remain sufficient for public and economic use until the end of the 2025/26 dry season. The Office of the National Water Resources (ONWR) confirmed on April 27, 2026, that the situation remains manageable despite the decline.

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Nationwide water storage currently stands at 48.39 billion cubic metres, representing 60% of total capacity, with usable water at 24.287 billion cubic metres, or 43%. Officials emphasised that while some reservoirs are under pressure, overall reserves remain adequate for ongoing consumption and economic activity.

The update comes as upper Thailand prepares for worsening weather conditions. Between April 28 and May 1, thunderstorms, strong winds and isolated hail are forecast, initially affecting the Northeast, North and East before extending to the Central region, Bangkok and surrounding areas.

Despite falling water levels, ONWR reported that water quality remains within acceptable standards. Tests conducted, showed salinity levels at all monitoring points were normal, with the Chao Phraya River at the Sam Lae pumping station meeting drinking water criteria. The Tha Chin River at Khlong Chinda, the Mae Klong River at Amphawa and the Bang Pakong River at Bang Taen all met agricultural-use standards.

Officials have urged residents, particularly in vulnerable areas, to stay alert and closely follow weather updates as conditions evolve. While the current outlook indicates sufficient supply through the dry season, continued monitoring of both reservoir levels and incoming rainfall will be essential.

The Nation reported that authorities are expected to maintain close surveillance of water reserves and weather patterns to ensure stability. Any significant changes in rainfall or demand could prompt further measures, though no immediate restrictions have been announced.

Key reservoir figures

• Total water nationwide: 48.39 billion cubic metres (60%)

• Usable water: 24.287 billion cubic metres (43%)

• Medium-sized reservoirs below 30%: 67 nationwide

Reservoir levels by region

West: 68% — 19.308 billion cubic metres

South: 64% — 5.017 billion cubic metres

North: 60% — 16.455 billion cubic metres

Northeast: 48% — 5.789 billion cubic metres

East: 37% — 1.125 billion cubic metres

Central region: 35% — 696 million cubic metres

In the Eastern Economic Corridor (EEC), key reservoirs remain at moderate levels:

• Prasae Reservoir: 172 million cubic metres (58%)

• Bang Phra Reservoir: 58 million cubic metres (50%)

• Nong Pla Lai Reservoir: 78 million cubic metres (48%)

However, six large reservoirs are now under close watch after falling below minimum control levels:

• Mae Mok Dam (North)

• Pa Sak Jolasid Dam (Central region)

• Khun Dan Prakan Chon Dam (East)

• Khlong Si Yat Dam (East)

• Vajiralongkorn Dam (West)

• Pran Buri Dam (West)

Picture courtesy of The Nation

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Adapted by ASEAN Now Nation 29 Apr 2026

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This is a result of Songkran.

1 hour ago, Georgealbert said:

authorities say supplies remain sufficient for public and economic use until the end of the 2025/26 dry season.

But aren't we expecting an unusually long dry season due to some El Ninio effect?

This year it's going to be brutal it looks like. here in the south, no substantial rain for 2 months already.

8 hours ago, Ralf001 said:

This is a result of Songkran.

Totally agree, happened before when this was mentioned and they asked to curtail water events for songkran, of course...no one listened.

1 hour ago, brfsa2 said:

This year it's going to be brutal it looks like. here in the south, no substantial rain for 2 months already.

Drill a bore hole - be self sustained and forget about everyone else.

1 hour ago, brfsa2 said:

This year it's going to be brutal it looks like. here in the south, no substantial rain for 2 months already.

Absolutely smashing it down here in Chonburi!

Off topic troll post removed.

@1tooth final warning - this is the news section, not for you nonsense trolling!

Rule 10. You will not post troll messages. Trolling is the act of purposefully antagonizing forum members by posting controversial, inflammatory, irrelevant or off-topic messages with the primary intent of provoking other members into an emotional response or to generally disrupt normal on-topic discussion.

16 hours ago, Ralf001 said:

This is a result of Songkran.

I would say no, most water used during Songkran, all the roadside players ,would be mains water that comes mainly from underground bore holes, not dams.

The op's photo is of the Pascack Jolaside dam, from last autumn by the way, that slip way is now dry, that water is used mainly by farmers for irrigation in the area and well downstream for rice farmers, I would say a lot would be lost though evaporation.

They have been building small reservoirs in the dam as big as 1-2 football/soccer pitches, trying to keep more water back.