Cal. Rev. & Tax. Code § 2189.6
Improvements that constitute component parts of a water distribution system located in whole or in part on property assessed to a person other than the assessee of the land on which they are located shall be assessed as improvements on the secured roll. However, those assessments shall not be a lien on the land on which those improvements are located and that fact shall be noted on the secured roll.
If the tax thereon is unpaid when any installment of secured taxes becomes delinquent, the tax collector may use the same collection procedures available for the collection of taxes on the unsecured roll.
If the tax thereon remains unpaid at the time set for the declaration of default for delinquent taxes, the tax together with any penalty and costs that may have accrued thereon while on the secured roll shall be transferred to the unsecured roll.
Ca. Rev. and Tax. Code § 2189.6