ONWR flags 7 provinces for high-tide watch from Jan 31-Feb 4, warns of flooding and saltwater intrusion

The Office of the National Water Resources (ONWR) has issued a warning for residents in low-lying riverside areas to prepare for high tides from January 31 to February 4, 2026. The agency said monsoon influences could push water levels higher, leading to overflow in vulnerable sections of flood defences and potentially affecting tap-water quality.

According to ONWR, two key phenomena during the period could affect communities along major riverbanks:

1) Risk of sudden riverside flooding

High tides combined with the northeast monsoon are expected to raise water levels in the Chao Phraya River, Tha Chin River, and Mae Klong River above normal.

Areas of concern include communities outside flood barriers, and areas along temporary embankments and sections without permanent protection (gap zones).

Main roads to watch include Sukhumvit Road, Suksawat Road and Rama II Road. These routes may see water pooling on road surfaces.

2) Saltwater intrusion risk

Higher sea levels may push saltwater further upstream, directly affecting water quality for household use and consumption, and potentially damaging crops in agricultural areas.

Relevant agencies are coordinating preparedness measures in areas assessed as high risk:

• Bangkok
• Samut Prakan
• Nonthaburi
• Pathum Thani
• Samut Sakhon
• Nakhon Pathom
• Samut Songkhram

Advice for residents

People living in low-lying areas, or in homes without permanent flood protection, are advised to move belongings to higher ground and closely monitor updates via ONWR’s channels or the Thai Water application.

• Check flood barriers: If you find damage or a gap section, report it to local officials immediately.
• Store drinking and household water: During saltwater intrusion, tap water may taste brackish at certain times.
• Plan travel: Avoid flood-prone routes, especially during peak high-tide periods.