PTT, the national oil and gas conglomerate, expects drought will impede production in Chon Buri and Rayong unless the rainy season delivers normal levels of precipitation.
The drought is projected to affect large swathes in the East, where three provinces -- Chachoengsao, Chon Buri and Rayong -- are being promoted in the government's Eastern Economic Corridor (EEC) scheme.
PTT's operations in both provinces are related to upstream and downstream productions for petroleum and petrochemicals.
President and chief executive Chansin Treenuchagron said PTT is evaluating possibilities and whether the 2020 drought will be similar to the experience in 2005.
Many companies in the eastern provinces recently voiced concerns about risks of drought recurring in 2020.
Local communities and fruit growers in Chon Buri and Rayong have blamed industrial operators for draining the water supply, leaving them with insufficient water for consumption.
Olefins manufacturers have halved their production amid the water shortage.
Mr Chansin said PTT has tentatively proposed to the Office of National Water Resources the use reverse osmosis technology to process seawater.
"The office should attract companies to participate in this proposed project and a public-private partnership should be set up for flexible management while working alongside the state-run Provincial Waterworks Authority [PWA]," he said.
New companies would help with supply, in addition to existing raw water supplier Eastern Water Resources Development and Management, while PWA distributes tap water.
"Seawater processing requires higher technologies and investment costs, but the government can adopt appropriate measures such as incentives and lowering water prices to balance costs and prices for buyers and sellers," said Mr Chansin.
"Although many EEC megaprojects are being developed, the water supply still depends heavily on the rainy season."
He said a stable water supply is crucial for Thailand's industrial sector and the proposed raw water plan offers additional supply of water resources.
"PTT is ready to participate in the raw water business, depending on business conditions," said Mr Chansin.
He said the 2020 economy will suffer from drought, the coronavirus outbreak and the delayed fiscal 2020 budget.
"The risks will lower demand for oil and gas below PTT's projection," said Mr Chansin.
PTT is considering reducing natural gas volume purchased locally and shifting to importing liquefied natural gas as global market prices are low, he said.