Colo. Rev. Stat. § 31-35-601
In addition to the powers already had by municipalities, they have the following powers: When the governing body of a municipality having a public sewerage system deems it necessary for the protection of public health that owners of one or more premises connect their premises with the public sewer, thirty days' notice in writing shall be given to said owners, by registered mail, notifying them to connect their premises with the sewer, the date of the notice to begin as of the date of registering the same for mailing. If the work of making the connection is not begun within thirty days, the mayor shall notify the municipal engineer to prepare plans and specifications for making the connection with the public sewer, including water and service pipe for flushing purposes, if the owner has given notice and proof to the governing body or mayor of his financial inability to make the connection himself and if it is only for the necessary connection of a water closet or a privy in an outhouse or both.
C.R.S. § 31-35-601
This section is similar to former § 31-35-501 as it existed prior to 1975.