Yes, but only to extent those rules are reasonably related to the safety of the tenant or to the safety of the landlord's property. A landlord must be very careful not to use age limitation on usage as an excuse to discriminate against families with children, which is a protected classification under federal and state Fair Housing laws. Obviously a rule that says a six year old cannot be unattended when near a pool would be held reasonable in virtually anyone's eyes. Conversely, a rule that says no one under the age of 21 could use any facility would be unreasonable in anyone's eyes. The exact line of reasonability of a particular age requirement is always a tough question. We generally recommend age 14 as the age that a child should be expected to reasonably use most communal facilities.