If my tenant did not report a leak, then what obligations do I have if the premise is uninhabitable?

I have a tenant that put a large armoire in front of the utility closet that houses the hot water heater. Today the hot water heater burst, but it appears to have been leaking for quite some time because the board under linoleum has rotted. I have the following provisions in the lease: Tenant... show more I have a tenant that put a large armoire in front of the utility closet that houses the hot water heater. Today the hot water heater burst, but it appears to have been leaking for quite some time because the board under linoleum has rotted.

I have the following provisions in the lease:

Tenant responsibilities:
Promptly reporting any defect, damage, or breakage to the Landlord. Failure to report shall make the Tenant liable for the repair of any additional damages. This provision does not obligate the Landlord to repair or correct such defects, breakage, malfunction of damage.

Landlord responsibilities:
LANDLORD MAINTENANCE. Except as otherwise noted the Landlord shall maintain the Premises in good repair and tenantable condition and shall be responsible for repairs not due to the fault or negligence of the Tenant during this Lease.

My questions are:

1) Would putting the armoire in front of the utility closet and not reporting the leak be considered negligence?

2) I may need to open up a big section of the floor and let it dry out before I can put in a new hot water heater. What are my legal obligations to the tenants?

3) I know the dangerous mold is rare, but if the health department deems the premise uninhabitable, am I liable to provide them with alternative housing?
Update: Oh, and I am in Virginia.
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