Recycled Water FAQ's
Recycled Water’s Role as a Resource
Recycled water is reclaimed wastewater that has been cleaned and disinfected so that it is safe to directly use for purposes that do not require drinking-quality (potable) water. Modern wastewater treatment processes restore the quality of large volumes of water quickly and effectively. The MWMC treats all of Eugene/Springfield’s wastewater under strict standards to return it to the Willamette River – or divert it for additional recycled water processing. The resulting recycled water is clear, clean, and safe for a variety of approved uses such as vehicle washing and landscape watering.
All water is continually recycled in nature through the water cycle. The Earth’s surface is 70% water. Of that, 97% is salt water and 3% fresh water with 1% available to use. The water we use today is the same water that has been here since Earth began. However, the natural water cycle is a slow process that can take centuries. Recycling water allows us to replicate that natural cycle and protect scarce surface water resources.
We recycle water for the same reasons we recycle other materials: to reduce waste and conserve resources. Recycling water is part of our responsible management of water supplies. Much of our water needs do not require potable (drinking-quality) water, and using recycled water reduces over-drawing our groundwater and streams. It also helps us meet environmental restoration and protection goals. Recycling water recycles nutrients found in wastewater, as well – providing a double benefit for plants irrigated with recycled water.
Around the world, across the nation, and here in Oregon, recycled water is used for environmental enhancement, such as wetlands, aquatic habitats, and stream flow augmentation. The MWMC’s recycled water use can help maintain cooler river temperatures needed by salmon by reducing the total flow of warmer water discharged to the river. The availability of recycled water can create new opportunities in the community for agriculture, industry, and public green spaces.
The water terms recycled, reclaimed and reused are often used interchangeably and mean basically the same thing. Recycled water specifically refers to treated wastewater cleaned to meet the standards for various levels of reuse. However, recycled water should not be confused with other types of reused water, such as untreated graywater collected from household sinks or recirculated water from industrial processes like cooling towers. In Oregon, the term “recycled water” indicates treated effluent from municipal wastewater that has been tested to ensure its quality and safety.
The Oregon Department of Environmental Quality regulates recycled water under strict treatment standards and permitting requirements. Under Oregon rules, recycled water is classified as Class A, Class B, Class C, or Class D based on its intended use and level of treatment. Each class requires consistent testing and monitoring for water quality. In reverse order, from most basic quality to highest quality of recycled water, these four classes are:
- Class D recycled water is suitable for non-food crop irrigation and is approximately the same water quality required of the MWMC’s cleaned wastewater to be returned to the Willamette River. The only difference is treated water discharged to the river is dechlorinated after disinfection, whereas recycled water remains chlorinated for use. The MWMC uses Class D recycled water at its Biocycle Farm for poplar tree irrigation.
- Class C recycled water achieves a higher level of disinfection than Class D. Class C has a wide variety of approved industrial, commercial, and agricultural applications.
- Class B recycled water requires a higher level of disinfection than Class C for specific uses, such as fire suppression and watering of golf courses and cemeteries.
- Class A recycled water requires additional filtration and the highest level of disinfection and is appropriate and safe for uses such as car washing, ornamental fountains, and for watering parks, schoolyards, and food crops. Essentially, Class A recycled water can be used for nearly any purpose where than drinking water quality is not necessary.
Production & Safety
Recycled water requirements in Oregon make it safe to use for any non-drinking water purpose. In desert and water-scarce regions of the United States, potable recycled water treatment operations for drinking water supplies are becoming more common. Depending on the level of treatment (Class A, B, C, or D) and other water quality characteristics, the most basic levels of recycled water are safe for non-food crop agriculture, while the highest level of treatment (Class A) is safe for publicly-accessed areas and food crops. Recycling water is a safe way to conserve our natural water resources. At a minimum, wastewater treatment ensures water returned to the Willamette River meets strict standards to protect human health and the environment. Recycled water meets or exceeds those standards.
Modern wastewater treatment uses processes of solids settling, biological action, aeration, and filtering, along with final disinfection, to clean reclaimed water quickly and effectively. These are largely the same processes of the natural water cycle. Untreated wastewater arriving at the treatment plant contains less than 1% pollutants – it is over 99% water. Of that 1%, the treatment process removes more than 97% of the solids and other pollutants, producing recycled water that is over 99.97% pure – prior to the additional filtration and disinfection to produce Class A recycled water.
The MWMC’s standard processes result in reclaimed water deemed suitable for many agricultural and industrial uses that is rated as Class C recycled water. To produce the highest quality of recycled water, the MWMC passes the initially treated water through additional filtration and ultra-violet light disinfection to provide ultra-clear, clean water for reuse as Class A recycled water.
All recycled water use is regulated and registered by the State of Oregon through the Department of Environmental Quality and the Oregon Water Resources Department. The Department of Human Services also reviews plans for use of Class C and D recycled water uses to ensure the protection of public health. Oregon has specific rules covering recycled water use defined by Oregon Administrative Rules Chapter 340 Division 55 (OAR 240-055).
All approved recycled water use sites have signs informing workers and the public that recycled water is in use and is not to be used for drinking. Nationally, all recycled water piping, including spigots and irrigation heads, is marked or painted purple (known as “purple pipe” in the water resources field). In Oregon, all recycled water producers operate under permit and a Recycled Water Use Plan filed with the Oregon Department of Environmental Quality and the Oregon Water Resources Department.
While recycled water is increasingly used for replenishing drinking water supplies around the world and in the U.S., Oregon’s current recycled water classes do not include drinking water quality standards. National standards have been developed for “direct potable reuse” of treated wastewater, and in Oregon and other regions, beer has been made from potable recycled water to celebrate the ability to do this. The MWMC’s recycled water does not go through the same level of treatment and testing done for drinking water. “Indirect use” applications do allow for recycled water to replenish drinking water aquifers, much the same way rainwater and streams do naturally. However, in the Eugene-Springfield community, the MWMC is evaluating opportunities for recycled water where drinking water quality is not required, such as for agricultural, commercial, and industrial applications. Eventually, groundwater aquifer replenishment with recycled water sources may be an important part of Oregon’s water resources strategy.
The Eugene-Springfield area has extremely high-quality drinking water sources, even before treatment which is performed by our local drinking water utilities. Additionally, while other regions can and do treat reclaimed wastewater to drinking water standards, it is not necessary, cost-effective, or energy-efficient to do so here. The benefit of recycling water in this area is that it helps conserve our drinking water and other water resources while reducing temperature and other impacts to the river. Therefore, our recycled water is cleaned to be safe for use and the environment, but it is not purified for human consumption.
Recycled water is reclaimed from treated wastewater and cleaned for safe use by further reducing harmful toxins, fine particulates, and bacteria. All water contains trace minerals and salts, and different water sources have different mineral characteristics. Some waters have high levels of iron, sulfur, or calcium that make them unsuitable for any purposes. Recycled water can contain chlorides or other salts that may make it unsuitable for certain types of irrigation, but certain nutrients retained in recycled water can be beneficial to plant growth. Increasingly, our water sources also contain traces of pollutants from the air and surface runoff – or in the case of recycled water, from substances washed down the drain. Water resource specialists call these trace chemicals “micro-constituents” due to their extremely small, but still detectable, presence.
Detectable micro-constituents include everything from caffeine to fire retardants. The good news is that only a few micro-constituents of concern are regularly found in treated wastewater (based on a legislated statewide study conducted by the Department of Environmental Quality). Class A recycled water processing decreases their presence even further. Studies have also shown that irrigation use can improve the breakdown and removal of micro-constituents through natural soil processes. In fact, vegetated wetlands and planters are used around the world as natural filtration systems to clean water – and they are increasingly used to treat urban stormwater runoff before it flows to our streams.
We are more aware of particulates and substances in our environment today because modern technology allows us to identify them in extremely low concentrations, not only in water, but in household dust and in the polar ice caps. These trace chemicals are a result of our use of medications, antibacterial soaps, health and beauty products, and other commonly used flame retardants, water repellents, plastics, and pesticides.
To reduce their presence, state and local governments have imposed regulations and launched public awareness campaigns to ban or reduce the use of certain products, call for collection and disposal stations (for unused medications and other items), and avoid pouring hazardous waste down drains or toilets. To reduce the amount of unwanted chemicals in the environment, consumers can look for safe product labels (such as the EPA’s Design for the Environment label), reduce the use of disposable products and plastics, and properly dispose of household chemicals and wastes.
Environmental Protection
Water recycling can provide multiple environmental benefits. Protecting human health and the environment is the foremost consideration for the MWMC. One way to enhance Willamette River water quality is to keep as much naturally cooler source water as possible in the river and reduce the amount of warmer, cleaned wastewater returned to the river. Using recycled water instead of river water or groundwater for irrigation and other uses not only reduces stress on our water resources but also helps maintain cooler water for native fish.
Recycled water can also be an integral part of our community’s environmental assets and resilience to climate change. Across the nation and around the globe, recycled water is used to create wetlands, enhance stream habitat, and irrigate urban trees and parks that help shade and cool cities on hot, dry, summer days.
Even during a typical dry season when river flows are among their lowest, the total volume of wastewater cleaned and returned to the river amounts to no more than 2.5% of the total river flow. Only a small portion of that would be diverted for recycled water use. The Willamette River’s lowest flow in a 10-year period is estimated to be around 1,400 cubic feet per second – or around 900 million gallons per day. The MWMC intends to initially recycle an additional 0.5 to 1 million gallons per day, less than 0.2% of river flow under the driest conditions. Additionally, strategic use of recycled water will offset the need to use river water from other sources – potentially having no net impact on total river flow. This practice will help retain more freshwater instream overall.
Water recycling protects our groundwater resources in several ways:
- It serves as a substitute for pumped groundwater sources and reduces over-withdrawal of our groundwater supplies.
- Irrigation with recycled water is carefully controlled under approved plans to apply only the amount of water needed for crops or landscaping, thereby minimizing potential for ongoing percolation to groundwater.
- However, if desirable, recycled water infiltration ponds or wetlands can be designed to replenish groundwater supplies under strict water-quality control requirements.
Uses & Opportunities
The MWMC has been safely producing and using recycled water for irrigation and system processes since the 1980s. The history and growth of recycled water usage in the United States goes back decades earlier though, with the first planned urban uses implemented in the 1960s in California, Colorado, and Florida. Well before that, recycled water was used at the Grand Canyon National Park for toilet flushing and lawn sprinkling (installed in 1926) and at San Francisco’s Golden Gate Park for irrigation and ornamental ponds (started in 1932). Oregon first adopted recycled water use rules in 1990. The U.S. Environmental Protection Agency (EPA) published its first guidelines for water reuse in 1980.
Recycled water is beneficial to a wide range of agricultural, industrial, commercial, institutional, environmental, and recreational uses. In Oregon alone, recycled water is in use in more than 120 communities, including over a dozen golf courses. The Oregon Gardens in Silverton thrive with recycled water further purified for irrigation use through a series of wetlands. In Hermiston, recycled water enhances the irrigation supply for organic farms. Elsewhere in the Pacific Northwest, Olympia, Washington uses recycled water for many purposes, including restoring wetlands, landscape irrigation, and toilet flushing. Numerous U.S. cities have installed dedicated recycled water piping systems for landscape irrigation. Recycled water makes San Antonio’s famed Riverwalk canal possible, providing almost all of the water flow during dry months.
The MWMC produces recycled water as part of its high-quality wastewater treatment process. Since the 1980s, this recycled water has been used to irrigate landscaping at the MWMC’s facilities and later at our Biocycle Farm poplar tree grove . The recycled water is also used for cooling and operation of the MWMC’s treatment process equipment. The MWMC recycles about 50-100 million gallons of water annually – equivalent to two to four days’ worth of our community’s cleaned wastewater. The capacity to supply more recycled water for community use is great.
The MWMC decided to upgrade its facilities to produce Class A recycled water – the highest quality recycled water – to provide this water resource to the community. To increase community awareness and knowledge of recycled water, the MWMC is demonstrating the safe and effective use of Class A recycled water through key initial projects. These demonstration projects include irrigation of publicly-accessible landscaping around the wastewater treatment plant, watering of city street trees, and piping water to nearby sand and gravel operations to use instead of river water.
Any new recycled water uses will reflect community needs and values and will be driven by public interest and demand. Recycled water could have a role in environmental restoration and operations, maintaining a healthy urban forest and green spaces, and industrial supply and business development.
Development & Partnerships
The MWMC historically has produced recycled water for non-public uses at the cost of pumping and piping it to points of use. To enhance basic recycled water to Class A quality, the MWMC engineered its existing filter units and seasonal million-gallon holding capacity to serve as Class A recycled water clarification and reservoir storage – cost-effectively using existing treatment plant infrastructure. The MWMC is adding ultra-violet (UV) light disinfection and new piping, pumps, and monitoring equipment to ensure consistent, reliable, Class A recycled water availability.
The initial investment in system upgrades is projected to cost $6 to $8 million, based on 2023 construction costs. This investment allows for additional capacity build out over time. Considering that the initial Class A production could produce 0.5 to 1million gallons per day for at least 6 months of the year, if not year-round, the 20-year investment cost is less than a half-cent per gallon, including operating and maintenance costs.
Water recycling is part of the MWMC’s everyday operations as well as an integral part of the MWMC’s key outcomes for environmental protection, reliable infrastructure, and community partnerships. As with all of its operations, the MWMC also strives for cost effectiveness. Most of the MWMC’s operating budget is ratepayer funded. In alignment with the MWMC’s Financial Plan (2019), the MWMC seeks grant opportunities to help pay for projects as available. When facility improvements are needed, the MWMC leverages ratepayer support by securing grants, bonds, and low-interest loans for long-term project construction and implementation. Bonds and loans are paid back over many years (typically 20), spreading the cost of the investments out among present and future users.
The MWMC initially programmed funding for recycled water projects in the early 2000s, and is diligent with how it invests those dollars. For example, in 2011, the MWMC partnered with the City of Eugene to install “purple pipes” in tandem with the riverbank trail system expansion. This created a gateway for future recycled water use north of the Randy Papé Beltline at a fraction of the cost of constructing it separately later.
With the exception of on-site irrigation and other uses at the wastewater treatment facility, all recycled water needs to be moved to points of use through pipes or in mobile tanks. The MWMC’s existing pipelines move Class D recycled water from the treatment plant on River Avenue approximately five miles away to the Biocycle Farm. Potential uses for Class D recycled water along the pipeline route or adjacent to the treatment plant or Biocycle Farm could require short “spur” pipelines to move water to the sites. On-site or “satellite” treatment facilities could enhance Class D recycled water to Class C or A if needed. A mobile tanker fill station at the wastewater treatment facility will allow for filling of watering trucks, tanker trucks, and other equipment to be used off site, such as for street trees and construction sites. Significant future uses may require construction of distribution piping.
Learn More
Informational Videos
Check out this video to learn more about the MWMC’s efforts to protect the health of our community and the environment in a sustainable manner.
Watch to learn more about the MWMC and how we clean wastewater for the Eugene-Springfield area.
Learn more about the lifecycle of our Biocycle Farm poplar trees, which are irrigated with recycled water.
