Ala. Code § 11-50-106

In the event the amount collected from the assessment under any ordinance authorizing the purchase of a sewer, sewers, or sewer system shall exceed the total cost and expense of the same, there shall be refunded to each of the parties affected by said assessment a proportionate amount of the excess upon demand made thereafter by said parties within 12 months after maturity or payment of the bonds authorized by this division.