Laundry facilities may be found in a common area accessible to all the tenants in the building, or each apartment or flat may have its own facilities. Depending on when the building was built and the design of the building, utilities such as water, heating, and electricity may be common for all the flats in the building or separate for each apartment or flat and billed separately to each tenant (however, many areas in the US have ruled it illegal to split a water bill among all the tenants, especially if a pool is on the premises). Outlets for connection to telephones are typically included in flats. Telephone service is optional and is practically always billed separately from the rent payments. Cable television and similar amenities are extra also. Parking space(s), air conditioner, and extra storage space may or may not be included with an apartment. Rental leases often limit the maximum number of people who can reside in each apartment. On or around the ground floor of the apartment or flat building, a series of mailboxes are typically kept in a location accessible to the public and, thus, to the letter-carrier too. Every unit typically gets its own mailbox with individual keys to it. Some very large apartment or flat buildings with a full-time staff may take mail from the mailman and provide mail-sorting service. Near the mailboxes or some other location accessible by outsiders, there may be a buzzer (equivalent to a doorbell) for each individual unit. In smaller apartment or flat buildings such as two- or three-flats, or even four-flats, garbage is often disposed of in trash containers similar to those used at houses. In larger buildings, garbage is often collected in a common trash bin or dumpster. For cleanliness or minimizing noise, many lessors will place restrictions on tenants regarding keeping pets in an apartment.