The worst case scenario could see people paying up to $3000 for a professional data recovery service but already there are several people on Facebook who have offered these services for free and others who will even donate spare computer parts.

Despite repeated warnings from computer security companies for people to keep regular backups of their personal data, most don't. And for those who do, it's likely that the backups are kept in the same place as the computer itself, which is no help if your house is flooded.

Insurance may cover the computer or digital camera itself but, as digital forensics specialist Graham Thompson said, all of the photos and other information stored on the hard drive or memory card is priceless.

Thompson said the worst thing anyone can do in the event of a waterlogged computer or laptop is to try and turn it on while it is still wet.

"Let it dry, that's basically what it boils down to," he said.

"Most hard drives now are absolutely vacuum sealed containers, so the only thing that can actually destroy the hard drive is if you ... turn it on with water still around it."

Thompson said those affected by the floods should let their computers air dry, remove as many covers as possible, and wipe the components down to remove any debris such as sand.

"With laptops it's probably a good idea to take the screws off any openable covers underneath, like the battery and memory compartments ... [and] wipe them because water can stay in there forever," he said.

The manager of CBL Data Recovery in Brisbane, Dicky Brauner, said her company hadn't had anyone approach it to recover their hard drive yet because people were likely not thinking about their computers at this stage.

But Brauner contradicted Thompson, saying that it was the wrong approach to wait until the computer dries out.

"A hard drive, if it's been completely in flood water – so that there's a chance that there's actually water inside that hard drive – shouldn't be allowed to dry," she said.

"It's a very tricky situation becasuse if the water has any silt [in it] and it's not clean water ... then there's a possibility that when it dries ... you'll see a water stain mark where it has dried," she said. "Well that looks like a mountain when you're trying to read it from a hard drive perspective because the head [reader] sits so close to the platter that it's not acceptable to it and what would happen at that point in time is that the head would stick to the platters and on power up it would likely rip the data right off the hard drive."

Brauner suggested that people keep their hard drive in an airtight container "until it can actually be cleaned professionally" or either in the water it was found in, distilled water or a damp cloth in an airtight container until it was brought into a data recovery lab.

To recover a hard drive with CBL Data Recovery ranges from $400 to $3000, Brauner said. It offers customers a free evaluation within 46 hours of a hard drive being brought in.

Another hard drive recovery specialist, Ontrack Data Recovery, which has an office in Brisbane this is now being evacuated because of the floods, said its hard drive recovery service ranged from $500 to $1500. It charges $90 for an evaluation which would show customers what was available to be recovered.

However, if you're lucky enough to have time to backup data before floods hit, computer security expert Chris Gatford said there were a number of online backup services such as Wuala and Carbonite that allowed people to store their data in the online "cloud", which they can then pull down from any computer.

"They say the best backup process is what's called 3, 2, 1 backup, so you have three copies of any important files, two different media types and one copy should be stored off-site," he said.

For those without enough time to backup their important data to the cloud, Gatford said people should just open up their PC, remove the hard drive, and take it with them.

Director of Australian online backup service Backup.com.au, Mike Klimczak, said that if "you've got time and you've got a screwdriver" then you should disassemble your computer case and “just take out the hard drive". Online services like Backup.com.au allow data to be "transported not just away from your office building but away from the state", Klimczak said, meaning their copy of your data won't be affected by a disaster.

Mike Cannon-Brookes, the Australian founder of Atlassian, one of the pioneers of online "cloud" services and applications, said in an ideal world people shouldn't be worrying about unplugging their desktop computer and running out the door with it.

"Think about what data you have that's really precious – photos, address books, things like that – and make sure you have at least a copy of that data backed up in the cloud; either Apple's MobileMe or put your photos on Flickr or Dropbox or any of those online services," he said.

"Be selective, don't backup your music – you can always get that again."