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Water glossary



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Water Glossary - R

  • Radioactive: Having the property of releasing radiation.

  • Rain: Water falling to earth in drops that have been condensed from moisture in the atmosphere.

  • Rain gage: Any instrument used for recording and measuring time, distribution, and the amount of rainfall.

  • Raw sewage: Untreated wastewater and its contents.

  • Raw water: Intake water before any treatment or use.

  • RCRA: Resource Conservation and Recovery Act - federal legislation requiring that hazardous waste be tracked from "cradle" (generation) to "grave" (disposal).

  • Reaeration: Renewing air supplies in the lower layers of a reservoir in order to raise oxygen levels.

  • Recarbonization: Process in which carbon dioxide is bubbled into treatment water in order to lower the pH.

  • Receiving waters: A river, ocean, stream, or other watercourse into which wastewater or treated effluent is discharged.

  • Recharge: The processes involved in the addition of water to the zone of saturation; also the amount of water added.

  • Recharge Area: An area where rainwater soaks through the ground to reach an aquifer.

  • Recharge zone: The area where a formation allows available water to enter the aquifer. Generally, that area where the edwards aquifer and associated limestones crop out in kinney, uvalde, medina, bexar, comal, hays, travis, and williamson counties and the outcrops of other formations in proximity to the edwards limestone, where faulting and fracturing may allow recharge of the surface waters to the edwards aquifer.

  • Recirculating cooling water: Recycling cooling water to greatly reduce water use by using the same water to perform several cooling operations.

  • Recirculation: Recycling water after it is used. Often it has to pass a wastewater purification system before it can be reused.

  • Reclaimed wastewater: Wastewater treatment plant effluent that has been diverted for beneficial use before it reaches a natural waterway or aquifer.

  • Reclaimed water: Wastewater that is treated and reused to supplement water supplies.

  • Recurrence interval: Average amount of time between events of a given magnitude. For example, there is a 1% chance that a 100-year flood will occur in any given year.

  • Recyclable: Refers to such products as paper, glass, plastic, used oil, and metals that can be reprocessed instead of being disposed of as waste.

  • Recycled water: Water that is used more than one time before it passes back into the natural hydrological system or is discharged into a wastewater system. Also referred to as recirculated water.

  • Redox: Shortened term for reduction/ oxidation reactions. Redox reactions are a series of reactions of substances in which electron transfer takes place. The substance that gains electrons is called oxidizing agent.

  • Reduction: A chemical reaction in which ions gain electrons to reduce their positive valence.

  • Regeneration: Putting the desired counter-ion back on the ion exchanger, by displacing an ion of higher affinity with one of lower affinity.

  • Renewable resource: Natural resource (e.g., tree biomass, fresh water, fish) whose supply can essentially never be exhausted, usually because it is continuously produced.

  • Reserve Capacity: Extra treatment capacity built into wastewater treatment plants and sewers to be able to catch up with future flow increases due to population growth.

  • Reserves: Amount of a particular resource in known locations that can be extracted at a profit with present technology and prices.

  • Reservoir: A pond, lake, tank, or basin (natural or human made) where water is collected and used for storage. Large bodies of groundwater are called groundwater reservoirs; water behind a dam is also called a reservoir of water.

  • Resident population: The number of persons who live in a State who consider the State their permanent place of residence. College students, military personnel, and inmates of penal institutions are counted as permanent residents. According to this definition, tourist and seasonal or part-time residents are considered nonresident population.

  • Residential water use: See domestic water use.

  • Residual chlorine: The available chlorine which remains in solution after the demand has been satisfied. Compare chlorine demand.

  • Residue: The dry solids remaining after the evaporation of a sample of water or sludge.

  • Resistance block: Type of soil moisture probe used to monitor soil moisture conditions to help determine when water should be applied.

  • Resolution: The breaking of an emulsion into its individual components.

  • Resource: A person, thing, or action needed for living or to improve the quality of life.

  • Retrofit: Replacement of existing equipment with equipment that uses less water.

  • Return flow: The water that reaches a ground- or surface-water source after release from the point of use and thus becomes available for further use.

  • Reuse: See recycled water.

  • Reuse system: The deliberate application of reclaimed water for a beneficial or other useful purpose. Reuse may encompass landscape irrigation (such as golf courses, cemeteries, highway medians, parks, playgrounds, school yards, nurseries, and residential properties), agricultural irrigation (such as food and fruit crops, wholesale nurseries, sod farms and pasture grass), aesthetic uses, ground-water recharge, environmental enhancement of surface water and wetland restoration, fire protection, and other useful purposes.

  • Reverse osmosis: A water treatment method whereby water is forced through a semipermeable membrane which filters out impurities.

  • Right of free capture: The idea that the water under a person's land belongs to that person and they are free to capture and use as much as they want. Also called the "law of the biggest pump".

  • Rinse sink: Apparatus used to remove debris and contaminants from products and equipment.

  • Rinsewater: Water used to remove debris and contaminants from products and equipment.

  • Riparian water right: The legal right held by an owner of land contiguous to or bordering on a natural stream or lake, to take water from the source for use on the contiguous land.

  • Riparian zone: A stream and all the vegetation on its banks.

  • River: A natural stream of water of substantial volume.

  • River basin: A term used to designate the area drained by a river and its tributaries.

  • Runoff: The amount of precipitation appearing in surface streams, rivers, and lakes; defined as the depth to which a drainage area would be covered if all of the runoff for a given period of time were uniformly distributed over it.

  • Rural water use: Term used in previous water-use circulars to describe water used in suburban or farm areas for domestic and livestock needs. The water generally is self supplied, and includes domestic use, drinking water for livestock, and other uses, such as dairy sanitation, evaporation from stock-watering ponds, and cleaning and waste disposal. See also domestic water use, livestock water use, and self-supplied water.

Water glossary