Chancellor Angela Merkel said Wednesday that Germany still had much to do in bolstering the country's flood defences as she toured a northern water-logged region battling historic river levels.

Merkel made her fourth trip to flooded zones in around a week, visiting Hitzacker in Lower Saxony whose 4,000 residents have been told to leave their homes despite an anti-flood barrier set up after devastating 2002 floods.

The defence system has prevented the swollen River Elbe gushing into the town and Merkel said it showed the protective measure was worth having but said "there remains a lot to do", pledging further steps.

She earlier went to Lauenburg, 40 kilometres (25 miles) southeast of Hamburg, where the town centre is covered by about 30 centimetres (a foot) of water.

The water level stabilised at around 9.5 metres (31 feet) overnight in the picturesque town of half-timbered houses but was still almost twice as high as normal.

Disastrous floods in Germany began to subside Wednesday after leaving at least 19 people dead in central Europe.

While the River Elbe has begun to stabilise, thousands of volunteers are still working to shore up sodden dykes and some 10,000 soldiers are still helping in flooded regions.

Merkel will meet Thursday with the heads of the 16 regional governments to discuss the extent of the damage and funding.

Even regions spared the flooding will be called upon to contribute to an aid fund, as well as the government, but the amount of the fund still has to be determined.

During the "worst-of-the-century" floods in 2002, a 6.5-billion-euro fund was set up which provided help for several years, a finance ministry spokesman said at a regular government news conference Wednesday.

He stressed no overall figure was yet known for the current flood damage.

In Hungary, which has seen the Danube reach perilous levels, waters continued to recede in Budapest, down to 8.2 metres from nearly 9.0 metres on Monday.

The peak reached Baja, 150 kilometres south of the capital, where the level hit a record 9.88 metres.

"Today we can say for the first time that we can beat this, which is why we need to fight once more, in Baja," Prime Minister Viktor Orban said.