air gap: a vertical space between a water or drain line and the
flood level of a receptacle used to prevent backflow or
siphonage from the receptacle in the event of negative
pressure or vacuum.
aquifer: an underground waterway that is replenished by
backflow: flow of water in a pipe or water line in a direction
opposite to normal flow.
backflow preventer: a device or system installed in a water
line to stop backflow from a nonpotable source.
blackwater: the wastewater from toilets
and kitchen sinks.
buffer: to shift pH to a specific value.
building footprint: the area of a building on the ground.
cistern: an above or below ground tank used to store water,
generally made of galvanized metal, fiberglass, ferrocement
disinfection: a process in which pathogenic (disease producing)
bacteria are killed by use of chlorine or physical processes.
diverter: a mechanism designed to divert the first flush
rainwater from entering the cistern.
erosion: the loss of topsoil that occurs as a result of run-off.
filtration: the process of separating particles of 2 microns or
larger in diameter from water by means of a porous substance
such as a permeable fabric or layers of inert material housed in
a media filter or removable cartridge filter.
first flush: generally the first 10 gallons of rainwater per 1,000
square feet of roof surface that is diverted due to potential for
flow rate: the quantity of water which passes a given point in
a specified unit of time, expressed in gallons per minute.
forcebreaker: an extension of the fill pipe to a point 1” above
the bottom of the cistern, which dissipates the pressure of
incoming rainwater and thus minimizes the stirring of settled
greywater: the wastewater from residential
appliances or fixtures except toilets and kitchen sinks.
groundwater: water found below ground that has seeped
there through spaces in soil and geologic formations.
hardness: a characteristic of groundwater due to the presence
of dissolved calcium and magnesium which is responsible for
most scale formation in pipes and water heaters.
hydrologic cycle: the continual exchange of water from the
atmosphere to the land and oceans and back again.
leaf screen: a mesh installed over gutters and entry points to
downspouts to prevent leaves and other debris from clogging
the flow of rainwater.
micron: a linear measure equal to one millionth of a meter,
or .00003937 inch.
nonpotable water: water intended for non-human consumption
purposes, such as irrigation, toilet flushing, and
pH: a logarithmic scale of values of 0 to 14 that measure of
hydrogen ion concentration in water which determines
whether the water is neutral (pH 7), acidic(pH 0-7) or basic
pathogen: an organism which may cause disease.
potable water: water which is suitable and safe for human
pressure tank: a component of a plumbing system that
provides the constant level of water pressure necessary for the
proper operation of plumbing fixtures and appliances.
rainwater harvesting: the principle of collecting and using
precipitation from a catchment surface.
roof washer: a device used to divert the first flush rainwater
from entering a cistern.
run-off farming: the agricultural application of harvested
rainwater involving a system of terraces that directs the
rainwater from higher to lower elevations.
sedimentation: the process in which solid suspended particles
settle out (sink to the bottom ) of water, frequently after
the particles have coagulated.
total dissolved solids: a measure of the mineral content of
xeriscape: a landscape practice which specifies regionallyadapted,
drought-resistant plants and other water-conservingtechniques.