When flooding is the landlord’s responsibility
In most cases, yes. When flooding comes from the building — a burst pipe, a roof leak, a failed water heater, or a backed-up drain — the landlord is generally responsible for the cleanup and repairs.
Water from the building's own systems or structure is the landlord's problem to address, including drying the unit properly so mold does not take hold. Responsibility can differ for a natural disaster or for flooding a tenant clearly caused, but ordinary flooding from plumbing, appliances, or the roof falls to the landlord.
A slow or incomplete cleanup that leaves moisture trapped in walls and floors can turn one problem into another, since mold can start within a day or two. The landlord is expected to dry and repair the unit, not just mop the surface. If your apartment flooded from a building problem and your landlord will not properly handle it, a free review can help.
This is general information about California tenant rights, not legal advice. Every situation is different.