Authorizing the installation of individual water submeters, used to determine the actual use of water, for each residential unit in an apartment house and mobile home parks; prohibiting the owner, operator, or manager of an apartment house, or mobile home park, or a contractor hired by the owner, operator, or manager, from imposing certain costs on a unit; authorizing the owner, operator, or manager of an apartment house or mobile home park to bill an occupant a certain amount under certain circumstances; etc.