Water is a precious resource here in the West, much too precious to use just once. That’s why Denver Water has a program to treat and recycle wastewater.
Recycled water has successfully been used across the country for more than 100 years to supply water for irrigation, commercial and industrial uses. There are more than a dozen water recycling programs in Colorado, and Denver Water operates the largest recycled water system in the state.
Denver Water's Recycling Plant treats and delivers billions of gallons of water every year for industrial and outdoor irrigation uses. Once build-out is complete, the recycled water system will free up enough drinking water to serve almost 43,000 households.
Recycled Water Treatment System
Recycled Water Quality Standards
Recycled Water Training
Frequently Asked Questions
Recycled water is wastewater treated to a standard that is suitable for irrigation and some commercial and industrial uses.
Water is a precious resource here in the West, much too precious to use just once. That’s why Denver Water has a program to treat and recycle wastewater.
The system augments Denver's water supply for domestic uses by reclaiming water that otherwise would 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.
Recycled water comes from reusable supplies and users are approved to irrigate any day of the week. They must follow Denver Water’s annual watering rules, which includes not watering between 10 a.m. and 6 p.m.
By building the recycled water system, Denver Water supplies recycled water that can be used for irrigation, industrial and commercial operations reserving the highest-quality water for drinking, cooking and cleaning.
Denver Water's recycled water system serves numerous parks, schools, golf courses and other operations throughout Denver, including:
- The Denver Zoo.
- Xcel Energy.
- Several schools.
- Golf courses.
- Numerous parks.
The recycled water program aims to get larger water users off the drinking water system. For this reason, recycled water is not available for single-family residential use.
Places using recycled water are clearly marked with signs identifying the water is recycled. Recycled water customers’ valve boxes, manhole covers, and newer sprinkler heads are purple.
Some customers, like Washington Park, City Park and the Denver Country Club, receive recycled water from ditch systems that are classified differently. Customers using these systems are not required to post signs or use purple irrigation equipment.
Graywater is the water that goes down the drain when you use showers, bathtubs, washing machines and bathroom sinks. It does not include wastewater from toilets, kitchen sinks and dishwashers . Graywater is captured, treated and reused on-site in homes or buildings. Recycled water is treated municipal wastewater and is suited for direct beneficial use. Denver Water manages all the treatment and distribution of recycled water.
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. Although Denver Water’s recycled water meets the most stringent state water quality standards outlined in Regulation 84, 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.
Recycled water is delivered to customers through a separate system of purple pipes. Denver Water conducts site inspections to provide advice on connecting to the recycled water system.
Regulation 84 requires Denver Water to inspect recycled water customer sites regularly and provide training to all customers to prevent cross-connections that could lead to contamination of drinking water.
Backflow prevention devices are required at recycled water sites to protect the drinking water system.
Although many species of turf grass, trees and shrubs are tolerant of recycled water, landscape management is an important aspect of recycled water usage for irrigators. Water quality for trees and shrubs is important in determining whether plants will thrive. Soluble salts (salinity), sodium, bicarbonate, pH, nutrient elements, boron and chloride are important water quality aspects that can affect vegetation.
The treatment plant is located in Commerce City a stone’s throw from its source Metro Water Recovery’s Robert W. Hite Treatment Facility, and a key customer, Xcel Energy. Operations began early 2004.
Edible Crops Pilot Project
The Colorado Water Conservation Board (CWCB) is partnering with Denver Water to fund research into the impacts of using reclaimed water (also known as recycled water) to irrigate edible crops with a focus on soil health, crop yield and food safety.
This project will help inform decisions on water sources supplying urban and rural agriculture at various scales across the state and region based on public health and economic factors. The research team will compare how the three types of crops absorb contaminants of concern (including PFAS and select pharmaceuticals) and inorganic contaminants (like metals and nutrients) by planting three types of crops: root (carrots), leaf (kale), and fruit (tomatoes). Two beds will be irrigated with reclaimed water, and two beds will be irrigated with potable water.
The research team consists of staff from CU Denver College of Architecture and Planning, Colorado School of Mines Department of Civil and Environmental Engineering, Denver Water Recycled Water Program and the Recycling Plant.
The pilot is funded for three years, beginning in 2023, and will be active during the Colorado growing season.