About a quarter of Bosnia-Hercegovina's four million people are without clean water after the worst flooding since modern records began, the foreign minister has said.
Zlatko Lagumdzija said the destruction was "terrifying" and compared it to Bosnia's 1992-95 war.
At least 35 people have died in Serbia and Bosnia in flooding caused by unprecedented torrential rain.
More victims are expected to be found as the waters recede.
"The consequences of the floods are terrifying," Mr Lagumdzija told a news conference.
"The physical destruction is not less than the destruction caused by the war."
He said more than 100,000 houses and other buildings were no longer usable and the road infrastructure was badly damaged.
He also said there had been about 2,000 landslides, some of which were on minefields left over from the war. Nearly 120,000 unexploded landmines remain in more than 9,400 carefully marked minefields.
But the weather has dislodged warning signs and in many cases loosened the mines themselves.
"During the war many people lost everything. Today, again they have nothing," Mr Lagumdzija said.
Bosnian civil defence officials said as many as 500,000 people had been evacuated or left their homes.
Rescue helicopters from the European Union, the US and Russia have helped evacuate people from affected areas.
North-eastern Bosnia is reported to be especially badly affected, with houses, roads and rail lines submerged.
In the town of Orasje, frantic efforts were being made to stop the swollen River Sava further surging through broken barriers.
The emergency commander in the town, Fahrudin Solak, said the decaying corpses of drowned farm animals now represented a major health risk.
Although the waters were receding in some areas, a new flood wave from the River Sava on Monday threatened Serbia's largest power plant, the Nikola Tesla complex, 30km (18 miles) south-west of the capital, Belgrade.
The coal-fired plant in the town of Obrenovac produces about half of Serbia's electricity, and soldiers and energy workers worked through the night to build barriers of sandbags to keep the water back.
Serbian emergency official Predrag Maric said the situation in Obrenovac was critical and on Monday the entire town was ordered to be evacuated.
Evacuation orders were also made for 11 villages along the River Sava ahead of the flood wave.
Officials say that three months' worth of rain has fallen on the Balkans in recent days, producing the worst floods since rainfall measurements began 120 years ago.
Serbian Prime Minister Aleksandar Vucic said further international aid was needed, particularly deliveries of food, clothing and bottled water.
Ahdin Orahovac, director of Bosnia's Mine Action Centre, told the BBC that their work had been put back years.
"We are faced with the biggest problem and disaster after the war," he said.
"All of our mine warning signs have been moved. We have to warn our local population that they shouldn't hurry back to their homes because there are many locations where landmines are now in new places."