Relentless rains have plunged Thailand's Ayutthaya province, home to a UNESCO-listed ancient city, into what residents say is its worst flooding in years.

Murky waters have turned residential areas into vast, dangerous canals, reaching depths of up to three metres (10 feet) and creeping up the ancient capital's iconic temple ruins and gilded shrines.

"I have to endure life. I don't know what to do," said Somkid, who eventually constructed a high platform on top of tables to create a safe, dry sleeping area instead of the boat.

But he said the situation was "inconvenient", enduring unusable toilets, subsisting on food donations and navigating dangerous currents in his boat.

"I hope the water will subside soon," he said.

The rainy season's floods affected over 60,000 of the province's households and killed 18 people this year, Ayutthaya's Disaster Prevention and Mitigation Office said Friday.

It said that 38 temples in the area were also affected.

Vichai Asa-nok, who had to move out of his flooded home to a temple-run shelter, said the waters "came fast, very fast".

"The situation has become very difficult," he told AFP, with the flooding more extensive and lasting longer than in previous years.

Residents claimed the unusual duration -- almost four months -- and severity were largely due to mismanagement.

Community leader Boonchob Thongseejud said that authorities failed to release water into nearby fields, effectively rendering villages a "rest stop for water" before it gushes south down the Chao Phraya river to Bangkok and into the Gulf of Thailand.

He said water levels had surpassed those seen in a 2011 crisis by approximately 40 centimetres.

While the government has offered 9,000 baht ($280) in aid per household affected, some residents felt it was not enough.

Vichai said the sum is barely enough to purchase basic materials such as plywood to elevate homes, let alone the up to 3,000 baht for cleanup.

"It should be in the tens of thousands," he said.