Cal. Pub. Cont. Code § 20612

Whenever a district has contracted to reimburse an installer for the installation of water system facilities, it may impose upon land and collect from any person owning the land, other than the land designated in the contract as proposed by the installer to be served therefrom, which may connect to and receive water service from or through said water system facilities, a reasonable charge representing the proportionate share of the estimated cost of replacement or the proportionate share of the total installation cost of said water system facilities which is fairly attributable to the land which may receive water service. An amount attributable to interest may be included in the charge at a rate not to exceed 4 percent per annum from the date of installation to the date of connection of other land to the facilities.