The short answer
Flood risk can come from rivers, surface water, groundwater, or coastal sources, and isn't always obvious from a viewing.
A property can sit well away from any visible river and still carry meaningful flood risk from surface water run-off or groundwater. This is exactly the kind of risk that's invisible on a dry day and expensive to discover after you've bought.
Why this matters for your purchase
Flood risk is covered in the environmental section of every PropM8 report, drawing on the same data sources insurers and lenders use, so it's visible before you offer, not after.