Industry Terms

100-Year Adequate Water Supply Designation

  • The Adequate Water Supply Designation signifies that Flagstaff has demonstrated physical supply availability for 100 years, legal rights to water, water infrastructure, as well as financial and water treatment capabilities.

Advanced Water Treatment

  • Advanced Water Treatment is an umbrella term that covers many of the new technologies used to treat reclaimed water. When a series of these techniques are put together (referred to in the industry as a treatment train) they are able to purify reclaimed water into safe high quality water which meets all Safe Drinking Water standards.
  • This process is also designed to remove Compounds of Emerging Concern (CEC), such as pharmaceuticals, personal care products, and endocrine disruptors, as well as viruses, bacteria and Cryptosporidium; leaving behind only pure safe drinking water
  • Treatment Train examples of Advanced Treatment include, Reverse Osmosis, Ozone Filtration, Membrane Filtration, UV Filtration and Ultrafiltration.


  • An aquifer is an underground layer of water-bearing permeable rock, rock fractures or unconsolidated materials (gravel, sand, or silt) from which groundwater can be extracted using a water well.

Class A+ Reclaimed Water

  • The highest quality reclaimed water as classified by ADEQ standards. Class A+ means that the water has been treated to the highest standards for reclaimed water, through multiple treatment steps including disinfection.


  • A diversion channel allowing water to pass without creating a flood, often a large-diameter pipe under a road.


  • Another word for wastewater, often referring to sewage.

Environmental Buffer

  • An Environmental Buffer is any environmental feature that can act as a natural water filter. This can include soil, rock layers, an aquifer, or surface water, any combination of which provides an extra step to the cleaning process before the water is treated. In the examples of indirect reuse shown above, both Lake Mary and the layers of earth between the surface and aquifer, work as environmental buffers.

Direct Potable Reuse (DPR)

Direct Potable Reuse Graphic

  • The Process of taking high-quality, safe drinking water produced in the advanced treatment purification process and adding it directly into the potable water supply. Find a more in-depth look at DPR

Indirect Potable Reuse (IPR)

  • The process of taking class A+ or Advanced Treated water to an aquifer (recharge and recovery) or surface water before drawing it out for treatment and distribution. This method utilizes environmental buffers to naturally filter water before it is treated at a water production plant.

Aquifer Recharge (Groundwater Augmentation)Aquifer Recharge Graphic

  • The process of taking Class A+ reclaimed water or Advanced Treated Water and injecting it into an aquifer to be drawn out again later. This allows the earth's crust to filter the water before reuse.
  • Find a more In-depth look at Aquifer Recharge.

Surface Water AugmentationSurface Water Augmentation Graphic

Defacto Reuse

The process of Defacto Reusedischarging reclaimed water into established drainages, allowing it to naturally filter as it works its way down through the earth to the aquifer. This is called an environmental buffer, and is the most commonly-used method to discharge reclaimed water.

Class A+ reclaimed water is currently discharged into the Rio de Flag where it percolates through the ground back into the aquifer. The aquifer is monitored to detect any impact on the water quality.


  • Large sewer lines that, in a combined system, control the flow of sewage to a treatment plant. In a storm, they allow some of the sewage to flow directly into a receiving stream, thus keeping it from overflowing onto the streets. Also used in separate systems to collect flows from main and trunk sewers and carry them to treatment plants.

Potable Water

  • Water that is safe to drink.

Purple Pipe

  • Flagstaff's reclaimed water delivery network, separate and distinct from its potable system. Purple pipes are an industry standard for reclaimed systems to make them easily recognizable.

Reclaimed Water/Recycled Water

  • Water that has been recovered from wastewater and cleaned so that it can be reused. Reclaimed water is commonly used for irrigation, flushing toilets, surface water and groundwater recharge, and can also be treated to drinking water standards.