DHAKA, Bangladesh (AP) – Mahmuda Khatun left her flood shelter in a small boat loaded with empty water containers, prowled her inundated neighborhood for a while, and came back emptyhanded. “No one had any water to give us,” she said.

With 40 percent of her city flooded, water is everywhere, but it is mixed in with sewage and undrinkable. The disaster, experts say, is largely man-made.

Bangladesh and its capital, Dhaka, lie in a flood plain, and annual deluges from mighty rivers fed by monsoon rains and melting Himalayan snow are natural.

But deforestation of distant mountains washes topsoil downhill and silts up the rivers that are supposed to channel the floodwater into the Bay of Bengal.

Since June, heavy monsoon rains and overflowing rivers have engulfed two-thirds of the Wisconsin-sized country – the worst flooding since 1998.

Then there’s a rapidly growing population demanding more housing and roads. Developers have filled lakes and canals that used to channel rain water and sewage to the rivers.

An inadequate and poorly maintained sewage system compounds the problem.

Sixty percent of the liquid waste generated in this city of 10 million people is disposed of through open channels.These often get clogged with solid waste, according to Dhaka’s Water and Sewerage Authority.

And Dhaka, surrounded by nine rivers, has only 54 pumps – about half what it needs – to pump rain water out of city areas.

When three-quarters of the city was deluged in a deluge in 1988, authorities began building mud, brick and concrete river embankments around the city. But the work stopped for lack of money.

So now, a 14-mile-long embankment protects only the west of Dhaka, while the east is waist-deep in water.

Mohammed Ali of the Bangladesh University of Engineering and Technology believes embankments are only an emergency remedy.

“In the long run, it will not work,” he said. “We cannot stop flooding, but we can reduce the damage incurred each year through early forecasting and preparedness.”

Bangladesh is a flat, delta land crisscrossed by 250 major river systems that drain southward from the Himalayas to the Bay of Bengal. It is also vulnerable to slight rises in the level of the bay, which may be accelerated by global warming. Deluges in 1988 and 1998 covered 60-70 percent of the country between August and September.

The experts fear that such devastating floods will continue unless Bangladesh, India and Nepal cooperate in managing the rivers they share.

Meanwhile, many of those less cautious than Mahmuda Khatun are getting ill drinking polluted floodwaters. A center for diarrhea-related diseases in Dhaka says it is treating some 500 to 600 people, mostly children, each day.

Relief workers are distributing drinking water at flood shelters, but don’t have enough. Health workers and the media are warning people to filter and boil water or use water-purifying tablets.