Diarrhoea, caused by polluted water or rotten food, accounted for 208 of the 1,010 deaths during more than two months of flooding, the worst in Bangladesh's history, officials said.
Other deaths were caused by drowning, snakebites, collapsing houses and mudslides, disaster management officials said.
But the death toll could "dramatically rise" if the fast-spreading diarrhoea epidemic was not contained, they said.
Areas where flood water had receded had been driven into an "unimaginable squalor of mud and filth where living a normal life is worse than a nightmare", one relief official said on Thursday.
Dhaka's Flood Forecasting and Warning Centre (FFWC) said floodwater would keep receding despite occasional rains.
"The ebb trend of the flood is quite strong with all rivers dropping their levels fast," one FFWC official said. "Usual late monsoon showers would make no difference."
The floods have caused severe damage to agriculture, industry and infrastructure in this poverty-ridden South Asian country.
Water Resources Minister Abdur Razzak said in a newspaper interview on Thursday that the disaster had mainly been caused by heavy rainfall in the upper reaches of the country's major rivers, including the Ganges, which flow from the Himalayas down through India and Bangladesh before emptying into the Bay of Bengal.
He added silting up of the rivers and the blockage of drainage systems had also been partly responsible for the country's most prolonged natural disaster.
The floods submerged three-quarters of Bangladesh, including half of the capital Dhaka, which came under further threat in recent weeks when a dike protecting one million of the city's residents looked like collapsing under surging floodwaters.
But the Dhaka-Narayanganj-Demra (DND) embankment has held up, and Prime Minister Sheikh Hasina said on Tuesday the government would build a new 50-km (30-mile) embankment to protect the capital.
Meanwhile, a voluntary organisation in Dhaka has launched a clean-up drive offering three kg of rice for every one kg load of polythene bags, which with other rubbish have clogged virtually all drains in the city of nine million.
"This is one way we plan to overcome the waterlogging in the city," said a member of the Sabujmati volunteer group.
Hasina has said fears of famine have been averted by a quick international response to a plea for aid.
The first ship carrying 15,000 tonnes of grain offered by the U.N. World Food Programme (WFP) is expected to arrive at Chittagong port on Saturday.
The shipment is part of WFP's pledge to provide 355,000 tonnes of emergency wheat. The United States will give 400,000 tonnes while the European Union and other nations have pledged 110,000 tonnes.
- Reuters - Thomson Reuters Foundation
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