Frequently Asked Questions

Recycled water is wastewater treated to a standard that is suitable for irrigation and some commercial and industrial uses. Denver Water's recycled water satisfies the Colorado Department of Public Health and Environment (CDPHE) Regulation 84 (PDF)  for specific state-approved uses.

The system augments Denver's water supply for non-consumption uses by reclaiming water that would otherwise be discharged to the South Platte River. Denver Water owns rights to a significant amount of water that the Robert W. Hite Wastewater Treatment Plant treats and discharges into the South Platte River. Before the recycled water system was built, this water was lost downriver. By building the recycled water system, Denver Water now supplies recycled water that can be used for irrigation, industrial and commercial operations that do not require the high quality of drinking water. 

Using recycled water also helps delay the time when it will be necessary to divert more water from the upstream watersheds and develop new mountain water supplies. Adding recycled water to Denver’s source of supply provides a lower cost alternative for industrial and commercial operations and irrigators. 

Recycled water results from the treatment of domestic, municipal or industrial wastewater and is suitable for a direct beneficial use under Colorado Dept. of Public Health and Environment regulations. Grey water is untreated wastewater from common household fixtures such as bathtubs, showers, lavatory fixtures, wash basins, washing machines and laundry tubs. Grey water does not include wastewater from toilets, urinals, kitchen sinks, dishwashers or laundry water from soiled diapers.

The treatment plant is located in Commerce City, a stone's throw from its source, the Robert W. Hite Wastewater Treatment Plant, and a key customer, Xcel Energy. Operations began early in 2004.

Denver Water's recycled water system serves numerous parks, schools, golf courses and other operations throughout Denver, including:

• The Denver Zoo
• Common Ground Golf Course
• Denver Public Schools
• Denver Country Club
• Washington Park

Recycled water is not currently available for residential use due to the additional infrastructure required to provide individual plumbing and regulatory requirements that would be burdensome for individuals.  Supplying fewer customers with large demands results in a more efficient and economical system. Denver Water is continuing to expand the recycled water distribution system to reach more customers.

Although Denver Water’s recycled water meets the most stringent water quality standards outlined in Regulation 84 (PDF), it should not be consumed. Incidental contact with recycled water, such as walking on grass after it has been watered, is safe for adults, children and pets.

In 2009, Denver Water was granted Category 3 water quality status under State Regulation 84 for recycled water, which is the highest quality water status under this regulation. 

Places using recycled water will be clearly marked with signs identifying the water as recycled. Valve boxes, manhole covers, and newer sprinkler heads will be purple. Some customers receive recycled water from ditch systems that are classified as waters of the state and are regulated by the Colorado Dept. of Public Health and Environment under Regulation 61 (PDF). Customers using these systems are not subject to Regulation 84 and are not required to post signs or use purple irrigation equipment. 

Recycled water is delivered to customers through a separate system of purple pipes. Before new customers begin using recycled water, Denver Water conducts site inspections to provide advice on connecting to the recycled water system. Regulation 84 (PDF) requires Denver Water to inspect customer systems each year and provide annual training to all customers to prevent contamination of drinking water by cross connections.  

Backflow prevention devices on drinking water systems at places that use recycled water are required to provide an extra measure of protection in ensuring that recycled water does not enter the drinking water system. Air-gap connections within the distribution system allow Denver Water to add drinking water to the recycled system for emergencies. The air gap makes it impossible for recycled water to enter the drinking water system. Denver Water’s Operating Rules and Engineering Standards provide additional information regarding the installation and use of recycled water.