A human can go for more than three weeks without food (Mahatma Gandhi survived 21 days of complete starvation), but water is a different story. At least 60% of the adult body is made of it and every living cell in the body needs it to keep functioning.
You cannot raise the rent if you and the tenant have agreed, usually in a written lease, on a certain amount. Usually, you and the tenant will agree on a certain amount for a specific period of time. Once that time period ends, you can raise your rent with 30 (thirty) days written notice. If you and the tenant never agreed on a specific period of time, you can usually raise the rent with 30 (thirty) days written notice.
A Florida landlord must give you three days to pay your rent in full, which does not include weekends or holidays. The landlord must deliver a written notice to you that indicates the total rent due. He can't evict you for nonpayment if you pay in full in time, but the landlord is not obliged to accept partial payments.