FIFTEEN hundred Ipswich residents have been moved into evacuation centres as the city prepares for its worst ever flood.

Queensland State Disaster Coordinator Ian Stewart says eight evacuation centres are currently open in the city with more residents expected as the Bremer River rises to an expected peak of 22 metres today.

Mr Stewart says the river was at 18.5 metres at 5.30am (AEST).

He said the rising Brisbane River broke its banks at Yerongpilly and Indooroopilly this morning but homes have not been affected so far.

Mr Stewart said curious residents who were turning up in flood affected areas for a first hand look at the situation were, in some cases, hampering the efforts of emergency workers.

About 900 people spent the night in evacuation centres scattered around Ipswich as the city awaits the flood peak feared to be bigger than 1974.

Of those, 370 spent the night at the main evacuation centre at the Ipswich Showground.

The expected flood peak has been revised down slightly - to 21.5 metres - but authorities don't know exactly when it will hit.

Ipswich mayor Paul Pisasale later said the town's flood peak levels had been revised down to 20.5 metres, making it similar to the 1974 levels.

After a four-year-old boy died when he fell out of a rescue boat and was swept away in floodwaters at Marburg, just west of Ipswich yesterday afternoon, Mr Pisasale said the priority was to make sure no more lives were lost.

"My job at the moment is to make sure there's no more loss of life," he told the Nine Network.

"It's about looking after people, making sure morale's high and worry about the roads and infrastructure later and we'll deal with that."

In a city of about 140,000 people, Mr Pisasale said more than 1,000 had spent last night in evacuation centres and more than 2,000 were staying with friends, family and at hotels.

"But the most important thing is the spirit of people, it's very high," Mr Pisasale said.

"The media has played an important role in that, they've kept everybody informed, so everybody can watch at home and know what's happening in their city."

He said people at one Ipswich evacuation centre held a singing competition on Tuesday night.

"So we're having a bit of fun and hopefully the spirit will remain high," Mr Pisasle said.