Your landlord must know about the bad conditions in your apartment. Your landlord has knowledge of bad conditions if:

• the problem existed before you moved into your apartment,
• your landlord actually sees the problem,
• you tell or write your landlord about the problem (it is always best to notify your landlord in writing),
• the Board of Health notifies your landlord about a problem,
• another tenant has notified the landlord about a problem that affects you, too, or
• the problem existed at the time a new landlord bought your building.