Skip to page body Home Customer Service How To Environment Projects & Programs About Us


This section borrows directly from an extensive list of terms and definitions from the State Water Resources Control Board (SWRCB)’s Division of Drinking Water Terms and Definitions for Potable Reuse. This was put together by the Advisory Group on Direct Potable Reuse. Please consult the full list using a direct link to their report here.

Advanced Treatment: This term is often used to mean additional engineered treatment after secondary or tertiary treatment of wastewater to remove contaminants of concern to achieve public health or specific beneficial reuse parameters. However, the amount and type of advanced treatment applied is subject to the application, site-specific parameters, and federal, state, or local regulatory requirements.

Advanced Oxidation Process (AOP): A set of chemical treatment processes whereby oxidation of organic contaminants occurs on a molecular level through reactions with hydroxyl radicals. The advanced oxidation process typically employs hydrogen peroxide, hypochlorite, ozone and/or ultraviolet light, which break down organic molecules into metabolites.

Constituents of Emerging Concern (CECs): Chemicals or compounds not regulated in drinking water or advanced treated water. They may be candidates for future regulation depending on their ecological toxicity, potential human health effects, public perception and frequency of occurrence.

Direct Potable Reuse (DPR): The delivery of purified water to a drinking water plant or a drinking water distribution system without an environmental buffer. Additional treatment, monitoring, and/or an engineered buffer(s) would be used in place of an environmental buffer to provide equivalent protection of public health and response time in the event that the purified water does not meet specifications.

Drinking Water: Water conveyed through pipelines to homes and businesses that is safe for human consumption and meets all federal, state, and local health authority drinking water standards. Water treatment and distribution facilities that produce drinking water require an operational permit issued by the federal, state, or other designated permitting authority.

Filtration: A process that separates small particles from water by using a porous barrier to trap the particles while allowing the filtered water to pass through.

Indirect Potable Reuse: The addition of recycled water to augment groundwater or surface waters. Groundwater and surface waters are considered environmental buffers for providing public health protection benefits, such as contaminant attenuation dilution, and time to detect and respond to failures before final treatment and distribution. Indirect potable reuse can used advanced treated water, but can also be accomplished with tertiary effluent when applied by spreading (i.e., groundwater recharge) to take advantage of soil aquifer treatment (SAT).

Non-potable Reuse: Includes all recycled or reclaimed water reuse applications except those related to water supply augmentation and drinking water (i.e., potable reuse).

Pathogen: A microorganism (e.g. bacteria, virus, Giardia or Cryptosporidium) capable of causing illness in humans.

Potable Reuse: A general term for the use of recycled water to augment drinking water supplies. Potable reuse, which covers both indirect and direct potable reuse, involves various forms of treatment options. Potable reuse can be the addition of advanced treated recycled water or purified water to augment a drinking water supply. This form of potable reuse utilizes advanced treatment technology in combination with either environmental or engineered buffers to ensure that all necessary public health requirements are met to allow the water to be used as a drinking water supply. Potable reuse can also be accomplished with tertiary effluent when applied by spreading (i.e., groundwater recharge) to take advantage of soil aquifer treatment (SAT).

Purified Water: Water that has passed through a wastewater treatment plant and a full advanced treatment plant, and has been verified through monitoring to be suitable for augmenting drinking water supplies.

Recycled Water: Water that is used more than one time before it passes back into the water cycle. For example, wastewater that has been treated to a level that allows for its reuse for a beneficial purpose such as irrigation. Recycled water is sometimes called “reclaimed water.” With additional treatment, including advanced treatment, recycled water can be used as a source of water for a drinking water supply (see potable reuse).

Reliability: The ability of a treatment process or treatment train to consistently achieve the desired degree of treatment, based on its inherent redundancy, robustness, and resilience.

Reverse Osmosis: A high-pressure membrane filtration process that forces water through semi-permeable membranes to filter out large molecules and contaminants, including salts, viruses, pesticides, and other materials.

Title 22 Standards: Requirements established by the California Department of Health Services for the production and use of recycled water. Title 22, Chapter 3, Division 4 of the California Code of Regulations, outlines the level of treatment required for allowable uses for recycled water.

Ultrafiltration: Ultrafiltration is a type of membrane filtration in which hydrostatic pressure forces a liquid against a semipermeable membrane. A semipermeable membrane is a thin layer of material capable of separating substances when a driven force is applied across a membrane.

Ultraviolet (UV) Disinfection: UV disinfection is a cost-effective and reliable technology that protects against pathogenic organisms. This includes protozoa, bacteria, and viruses. (adapted from Treatment Plant Operator Magazine).

Water Reuse/Recycled Water: Water recycling is reusing treated wastewater for beneficial purposes such as agricultural and landscape irrigation, industrial processes, toilet flushing, and replenishing a ground water basin (referred to as ground water recharge). Water recycling offers resource and financial savings. (US EPA , Water Recycling and Reuse) The terms “reused” and “recycled” are often used interchangeably depending on where you are geographically. (WateRuse Glossary)

Last updated: 12/30/2019 12:14:12 PM