Bangkok plan could remove five flood-retention ponds

Bangkok's proposed new comprehensive plan would remove floodwater-retention designations from five pond sites and reduce conservation land in parts of the capital, the Thailand Consumers Council (TCC) has warned.

The fourth revision of the Bangkok Comprehensive Plan is open for public comment until November 9, 2026. Foreign residents who own, rent or are considering buying property in Bangkok may wish to check whether proposed zoning changes affect their neighbourhood, as the plan could influence future building density, traffic and flood risk.

Five ponds lose retention designation

The Bangkok Metropolitan Administration's planning update lists five sites that would lose their floodwater-retention designation: ponds at Chuan Chuen Bang Khen housing estate, Maniya housing estate, Suan Siam, Chuan Chuen Parkville housing estate and K.C. Lake View housing estate.

The BMA said the designations no longer reflected current conditions. The proposed amendment concerns the sites' planning function and does not, by itself, mean the ponds have physically disappeared.

Kongsak Sahasakmontri, a member of the TCC's subcommittee on real estate and housing, said Bangkok was steadily losing land that can hold floodwater during heavy rain, upstream flows and high tides.

He said the current 2013 plan marked areas in western Bangkok as rural and agricultural conservation zones, shown by green diagonal hatching on maps. These areas also acted as floodwater basins, commonly known as "monkey cheeks".

Under the draft revision, Kongsak said those western conservation zones would disappear and be replaced with yellow and orange residential zones, potentially allowing more housing estates and condominiums.

"The question is, if upstream water, rainfall and high tides arrive together one day, where will Bangkok find the space to hold that water?" he said.

Concerns over denser development

Kongsak also pointed to planned reductions in green-hatched conservation areas in Nong Chok, Min Buri, Khan Na Yao, Sai Mai and Lat Krabang in eastern Bangkok. He said open land, retention areas and projects in low-lying districts were being removed or reassigned for denser housing.

The eastern Khu Bon water-retention basin has already been removed from Bangkok's city plan.

Without these areas, Kongsak said Bangkok would become increasingly reliant on canals, drainage tunnels and pumps. While such infrastructure can ease flooding, he said recent inundation had shown its limitations when water volumes are high.

Water-management specialist Asst Prof Sitang Pilailar said the city should drain canals and other systems during low-tide periods, creating capacity before further rainfall and upstream water arrive. She warned that high tides from late September into early October could make drainage harder.

The Royal Irrigation Department forecast on September 23 that flows at Nakhon Sawan's C.2 monitoring station could reach about 1,800 cubic metres per second. Its September 26 report recorded 1,827 cubic metres per second, while Chao Phraya Dam released 1,850 cubic metres per second that day and 1,950 cubic metres per second on September 27.

How to object to the draft

The 90-day public-display period runs from August 10 to November 9, 2026. Interested parties may request amendments, changes or revocation of land-use provisions under Section 30 of the Town Planning Act 2019.

Kongsak said many residents did not yet understand how changes could affect flooding, traffic, building density, data centres, entertainment venues, potentially unlawful buildings and community quality of life. The TCC is preparing a campaign to help people understand the draft before objections close.

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1 October 2026