Colo. Rev. Stat. § 30-20-418
The entire costs of all sewerage and water connections, closets, equipment pipe, sewer pipe, labor, and necessary engineering, legal, and publication expenses shall be ascertained by the board of county commissioners, including an amount of six percent additional for costs of inspection, collections, and other incidentals. The cost to each owner shall be determined according to the material used and work done under the contract in connecting such property to the public sewer and water main. The engineering, legal, and publication expenses shall be charged in proportion as each connection bears to the whole. The cost to each owner shall be billed to him and if unpaid shall be collected in the same manner as other rates, fees, tolls, and charges of the system.
C.R.S. § 30-20-418