By Roland Buerk
BBC correspondent in Dhaka
Concern is growing about the spread of disease in Bangladesh's flooded capital, Dhaka.
Weather experts say the flood situation could get worse
About 40% of the city is under water and in places the sewage system has failed, with brown and stinking water flowing through the streets.
Already thousands of people are complaining of diarrhoea.
As monsoon rains continue, millions of people in the city get their drinking water from tube wells and the fear is that many are becoming contaminated.
The situation has got so bad that even the tap water is beginning to smell.
Many have had to leave their homes in search of drier ground
The floods have made life especially difficult for the very poorest in the city.
Slums are built on low-lying ground and most have been under water for days.
Some people have moved out to find dry land, building makeshift shelters from plastic sheeting and bamboo on the pavements in areas that are on higher ground.
In some parts of the city boats are now the only way to get about.
People buying them are complaining that prices have doubled in the last few weeks.
Flood forecasters say there is no relief in sight.
The rivers in the central area of Bangladesh that includes the capital are likely to rise further in the coming days.