Iowa Code Title IX. Local Government [Chs. 331-420] § 357.19. Completing assessment

After the final acceptance of the work by the board of supervisors, the engineer shall complete the final assessment, which shall be made on all the property within the district, whether abutting or not, for an amount approximately ten percent greater than the total cost of the project. The assessment shall not exceed benefits conferred and shall take into consideration the location and value of the property assessed. Where a pipe in excess of six inches in diameter is used, the assessment against the abutting property shall be limited to the cost of a six-inch pipe, and the difference between the cost of the pipe used and a six-inch pipe shall be paid by a uniform assessment against all benefited property within the water district. The final assessment on any lot or parcel of land shall not exceed the final preliminary assessment by more than ten percent, and shall in no case exceed twenty-five percent of the actual value of the property. The board of supervisors may alter an assessment to increase or decrease it within the limits outlined above, and must approve by resolution the final assessment as made.