Monday's heavy rain left behind neighbourhoods full of flooded cars in parts of Cape Breton, and soon their owners will have to sort out whether their vehicles are a writeoff.

How high the water reached will in part determine whether a vehicle can be saved, says automotive consultant Doug Bethune.

If it didn't reach the vehicle's axles and rocker panels, there shouldn't be any problems. Rocker panels are horizontal pieces of steel located underneath a vehicle's doors.

"Most of the vents for all those components are up higher than the centre of the axle," Bethune said on CBC's Maritime Noon.

While some cars can be saved, others can't.

Bethune says owners shouldn't drive their vehicles if water has gone above the axles and rocker panels.

Vehicle rocker panel

The rocker panel on a vehicle is the horizontal beam (shown in black) underneath the door. (CBC)

Instead, they should have the vehicle towed to a repair shop to flush fluids, such as the engine-lubrication oil, power steering fluid and transmission fluid.

Bacteria problems

If the interior of a vehicle is flooded, that's likely bad news because it may contain bacteria.

"If that bacteria and the spores are not killed off, then you're going to end up with respiratory trouble and bacteria airborne-related problems in the vehicle," said Bethune.

Even once an interior has been cleaned out, Bethune recommends getting an ozone treatment done to kill any bacteria and spores that may remain.

Saltwater is especially problematic because it can corrode electrical components and the vehicle's wiring.

Call your insurer

Bethune recommends people call their insurer to fully understand the process before any work is done.

"After the claim's been completed, you can't go back and say, 'Well, you missed this,'" he said.

If a vehicle is written off due to flood damage, Bethune says the owner should call Access Nova Scotia and report it. This will help brand the vehicle as flood damaged and helps ensure someone else doesn't purchase it without knowing its history.

He says some people buy vehicles damaged by flooding, fix them up and sell them to people without disclosing what they've been through.

With files from Maritime Noon