Conn. Agencies Regs. § 25-128-54
All wells and geothermal systems shall be maintained in a proper condition to conserve and protect Groundwater resources, and shall not be a source or cause of contamination or pollution of the water supply of any aquifer. All materials and construction practices used in the maintenance, repair, or replacement of any well shall be the same as those required for the construction of a new well or geothermal system. All maintenance, repair, hydrofracturing, developing, and replacement work shall be done only by a person holding the appropriate registration issued by the department pursuant to section 25-129 of the Connecticut General Statutes, or by a licensed plumber or electrician acting within the scope of the person's license, as provided by section 25-129 of the Connecticut General Statutes.
Conn. Agencies Regs. § 25-128-54