(a) A governing body may, with respect to any assessment district created by it, modify, expand or extend the boundaries of the assessment district to develop, construct, improve or extend any project, or to enable persons residing or engaged in business on property located outside the assessment district to obtain the services provided by a wastewater or water facility, (1) by satisfying the same requirements provided in this article for the creation of the assessment district, or (2) upon the unanimous written agreement of persons owning all of the property to be added to the assessment district that such property be added to the district and assessed in accordance with subsection (b) of this section: Provided, That no property may be added to an assessment district for connection to a wastewater or water project unless it abuts the assessment district.

(b) Any property added to an assessment district shall be assessed for and bear a proportionate share of the cost of the project then remaining unpaid, consistent with the concepts and principles set forth in sections eleven and twelve of this article and the assessment so laid shall be a lien upon the property in the same manner hereinabove provided from the date such assessment is laid. Contemporaneously with the resolution laying the assessment against such property, all other property located in the assessment district shall be reassessed to reflect the addition of such property to the assessment district. In all such cases, the assessment district shall be the holder of the assessment certificates issued to evidence the assessments laid upon the added property, and all assessment fees received by the sheriff from such assessment certificates shall be applied, pro rata, to reduce the final installment of principal and interest due from the owners of all other property located in the assessment district as it existed prior to the addition of property to the district.

(c) If any property is connected to a wastewater or water project after the cost of the project has been paid in full and the transfer of the project to a utility or governmental agency pursuant to section twenty-one of this article, the owner of such property shall pay to the utility or governmental agency the same rates and charges paid by other customers of the utility or governmental agency for the services provided by the wastewater or water facility operated and maintained by it.