More than 700 factories in the Amata Nakorn Industrial Estate in Chon Buri have been cautioned to monitor the floods closely, as they may face a repeat of the 2011 deluge.
Viboon Kromadit, the estate's chief of operations, said evacuation should be prepared and drilled even though the water has yet to affect their operations.
Yesterday he said the estate has seen minor flooding in phases 7-9 where 200 factories are located.
"At this level, the floods are manageable and the water has receded to 10 centimetres this week from 15 cm last week. But we should prepare for the worst by making emergency plans for equipment and facilities," said Mr Viboon. "The factories here have been warned to get ready for a crisis. Our team is closely monitoring the situation."
Its 40 units of feed pumps are prepared and all six canals around the areas were excavated to be ready for immediate drainage.
Mr Viboon said all factories in the estate are operating normally. However, Amata has alerted its clients with the warning yellow sign and stands ready to step up to red _ which means clients should evacuate _ if there are signs of further flooding.
He said the estate can handle as many as 1 million cubic metres a day.
Amata Nakorn, the biggest industrial estate in Thailand, serves nearly 700 factories with a total area of 20,000 rai. It has a combined manufacturing investment of 1.2 trillion baht with around 400,000 employees.
Chief executive Vikrom Kromadit said if the situation grows worse, the park will be divided into two sections and a temporary floodway will be built to allow the water to flow through.
Mr Vikrom said this was the first time floods had hit Amata Nakorn.
Suparat Sirisuwanangkura, chairman of the Federation of Thai Industries' auto industry club, said automotive production at Amata Nakorn is not affected.
Most of the manufacturers Japanese auto-parts makers such as Toyota, but there are no car makers.
Mr Suparat said the club is closely monitoring the flood situation in not only Chon Buri but also Ayutthaya, where the Saha Rattana Nakorn Industrial Estate is located.
As well, the auto-parts makers have raised their production output to ensure they have enough inventories in case logistic routes are disrupted by floods, he said.
Reuters said authorities say floodwater is moving in a different direction from that in 2011, when water flowed towards Bangkok from the North.
"It is heading towards the eastern provinces, so there's a chance industrial parks that were not hit last time could face flooding this time around," said Chatchai Promlert, director-general of the Disaster Prevention and Mitigation Department.
The department said floods this year have affected 28 of Thailand's 77 provinces, killing 36 people.
More than 3 million have people affected since July.
Toyota is weighing up risk-management strategies for one of its three Thai assembly plants, the Ban Pho facility in Chachoengsao province.
"Ban Pho is in an at-risk area at the moment, but we believe the factory will be spared from flooding," said Mr Chatchai.
Flooding in 2011 swamped seven industrial estates in the Central Plains, but many of the estates hit then say they are better prepared this time.
Rojana Industrial Park Plc said none of its three industrial estates have been affected by flooding this year.
"We are concerned, but we have built concrete barriers up to seven metres high around our estates and hired a specialist water management company to update us on weather patterns," director Amara Charoengitwattanagun told Reuters.
The firm's industrial park in Ayutthaya province was flooded in 2011, forcing the temporary closure of nearly 200 factories including one run by the Japanese car maker Honda Motor Co.
Industry Minister Prasert Boonchaisuk said he is confident that industrial estates swamped by floodwater in 2011 will not be affected, partly because rain so far has been less heavy.
Thailand is the world's largest producer of hard disk drives and a big supplier of electronic components and car parts.
Flooding in 2011 killed more than 800 people and caused major disruption to industry, cutting economic growth to just 0.1%. Global firms including Apple Inc and Toyota Motor Corporation also faced supply disruptions.