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.
waters: A river,
ocean, stream, or other watercourse into which wastewater or treated effluent
Recharge: The processes
involved in the addition of water to the zone of saturation; also the amount
of water added.
Area: An area
where rainwater soaks through the ground to reach an aquifer.
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.
Recycling cooling water
to greatly reduce water use by using the same water to perform several cooling
Recirculation: Recycling water
after it is used. Often it has to pass a wastewater purification system before
it can be reused.
treatment plant effluent that has been diverted for beneficial use before it
reaches a natural waterway or aquifer.
that is treated and reused to supplement water supplies.
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.
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
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.
resource (e.g., tree biomass, fresh water, fish) whose supply can essentially
never be exhausted, usually because it is continuously produced.
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
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.
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.
water use: See
domestic water use.
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.
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
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
osmosis: A water
treatment method whereby water is forced through a semipermeable membrane which
filters out impurities.
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.
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.
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.
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