Article 12 of the Colorado Primary Drinking Water Regulation states that "a public water system shall have no uncontrolled cross-connections to a pipe, fixture, or supply, any of which contain water not meeting all applicable provisions of the Colorado Primary Drinking Water Regulations."
A cross-connection is any source where water potentially containing biological, chemical or radiological contaminants could come into contact with the public water supply. This could potentially happen during an incident of backflow, when water inside a building or used for irrigating landscaping can be pushed (backflow) or drawn (back siphonage) back into the public water supply.
If an uncontrolled cross-connection is discovered and deemed hazardous, the water service in question will be shut off and the Colorado Department of Health will be notified. The service will remain off until such a time as the problem is deemed rectified by the City of Glendale, Denver Water, and the Colorado Department of Health.