Pump, Rotary. A type of displacement pump consisting essentially of elements rotating
in a pump case which they closely fit. The rotation of these elements alternately draws
in and discharges the water being pumped. Such pumps act with neither suction nor
discharge valves, operate at almost any speed, and do not depend on centrifugal
forces to lift the water.
Pump, Vertical Turbine Well. A centrifugal pump adapted for deep well use, consisting
of a series of stages, each stage comprising a set of vanes in a case or bowl. The
number of stages increases with the operating head.
Radius of Influence. The distance from a well, or group of wells, during pumping, within
which the water table or other piezometric surface is lowered by withdrawal of the
water. The area varies in extent with the rate and duration of pumping.
Rate of Flow. The volume of water per unit of time which is passing a certain
observation point at a particular instant. Common expressions are cubic feet per
second (cfs), gallons per minute (gpm), gallons per day (gpd), million gallons per day
Raw Water. Untreated water; usually the water entering the first treatment unit of a
water treatment plant. Water used as a source of water supply taken from a natural or
impounded body of water, such as a stream, lake, pond, or groundwater aquifer.
Recarbonation. The diffusion of carbon-dioxide gas through water to restore the
carbon dioxide removed by adding lime to water in water softening.
Recharge Basin. A basin excavated in the earth to receive the discharge from streams
or storm drains for the purpose of replenishing groundwater supply
Rem. The unit of dose equivalent from ionizing radiation to the total body or any
internal organ or organ system. A "millirem" (mrem) is 1/1000 of a rem.
Reservoir. A pond, lake, tank, basin, or other facility, either natural in its origin, or
created in whole or in part by the building of engineering structures, which is used for
the storage, regulation, and/or control of water.
Runoff. (1) In the general sense, that portion of the precipitation which is not absorbed
by the deep strata, but finds its way into the streams after meeting the persistent
demands of evapotranspiration. (2) That part of the precipitation which runs off the
surface of a drainage area and reaches a stream or other body of water or a drain or
Sanitary Survey. Study of environmental conditions of a water source or system which
might affect its potability or safety.