California Code, Water Code - WAT § 25932

(a) A receipt which specifies when applicable, (1) the amount of the assessment or charge, (2) the amount paid, and (3) the description of the property assessed.

(b) A statement or bill for the assessment or charge owed the district, with a stub or a copy of the bill which specifies when applicable (1) the amount of the assessment or charge, or if the assessment or charge is payable in more than one payment, the amount due with each payment; (2) a description of the property assessed; and (3) instructions that a receipt will be supplied only upon request since the stub or copy of the bill and the canceled check for payment constitute a receipt.