Three months of heavy monsoon rains have deluged around one in three provinces in central and northern Thailand, causing floods several metres deep in places and leaving around 300 people dead.
Tens of thousands of people have been forced to seek refuge in shelters as rising waters swallowed homes and businesses and shut down industry.
Flood Relief Operation Command (FROC) said in a statement it was "confident flood waters will not reach Bangkok", with water being diverted through a complex system of rivers and canals around the city.
It said the situation was "largely under control".
But irrigation department director general Chalit Damrongsak warned that the situation remained critical as water from low-lying areas north of Bangkok still needed to drain to the sea.
"It is not over," he said when asked about the crisis.
The floods have dealt a heavy blow to Thailand's economy, disrupting production of cars, electronics and other goods.
Water began leaking into the Navanakorn industrial estate in Pathum Thani, 45 kilometres (30 miles) from Bangkok, on Monday as authorities battled to reinforce barriers.
Flood Relief Operation Command ordered an evacuation of the site, which houses over 200 factories for both local and international firms.
Efforts to protect Thailand's capital have left areas outside the city to bear the brunt of the flooding.
Prime Minister Yingluck Shinawatra has asked the country's military to take charge of the emergency response in five of the kingdom's worst-hit provinces, including the low-lying historic city of Ayutthaya, which has been under water for over a week.
Thai authorities said water levels were receding in Ayutthaya, which lies about 80 kilometres (50 miles) upriver of Bangkok and has seen its ancient World Heritage temples and all five of its industrial estates swamped.
Agriculture minister Theera Wongsamut has said there were "good signs" that the situation would improve after a large amount of run-off water from the north flowed past Bangkok to the Gulf of Thailand on Saturday.
He added that water levels would be "stable" from now on, easing fears over a seasonal high tide that is expected to continue on Monday before subsiding and will make it harder for water to flow out to sea.
The next high tide period will be between October 28 and 30, officials said.
Conditions in Bangkok remained mostly normal and Suvarnabhumi Airport -- the capital's main air hub, which has floodwalls several metres high -- was operating as usual.
Japanese automakers including Toyota have suspended production in the kingdom due to water damage to facilities or a shortage of components.
The floods have also damaged 10 percent of Thailand's rice paddy.