Glossary

Glossary

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There are currently 234 names in this directory
Acre-foot
A volume of water that would cover one acre to a depth of one foot, or 325,850 gallons of water.

Adaptive plants
Non-indigenous plants that easily adapt to the climate and thus require little or no supplemental irrigation once established.

Adjusted water budget
An amount of water used to maintain a landscape that is based on area and ET rate.

Agricultural irrigation
Water distribution systems and practices in agriculture.

Air heat exchange
Cooling method, involving no water loss, during which a fan blows air past finned tubes carrying re-circulating cooling water.

American National Standards Institute (ANSI)
An association involved in developing standards for a wide range of products including plumbing fixtures.

American Society of Mechanical Engineers (ASME)
A professional organization whose Codes and Standards Committee helps to write and publish ANSI standards.

American Water Works Association (AWWA)
A professional organization serving the drinking water supply profession.

American Water Works Association Research Foundation (AWWARF)
A non-profit organization that sponsors research for the drinking water supply profession.

Anti-Siphon Valve
A control valve with a built-in atmospheric vacuum breaker (backflow preventer). Most commonly used in residential irrigation systems.

Application efficiency
The ratio of the average depth of irrigation water infiltrated and stored in the root zone to the average depth of irrigation water applied, expressed as a percent.

Application rate
The amount of water delivered to a given area, typically expressed in inches or inches per hour for irrigation.

Applied water
Water applied by irrigation, usually expressed as a depth of water in inches or feet.

Aquifer
Underground water-bearing geologic formation or structure.

Arable
Having soil or topographic features suitable for cultivation.

Arid
A climate characterized by less than 10 inches of annual rainfall.

Artificial recharge
The intentional addition of water to an aquifer.

Audit (end-use)
A systematic accounting of water uses conducted to identify opportunities for improved efficiency.

Automatic irrigation
Delivery of water to a landscape using a timer, a system of valves, and sprinklers.

Automatic irrigation controller
An irrigation timer capable of operating valve stations to set the days and length of time of water applications.

Automatic Valve
An irrigation valve which can be remotely operated. The remote operation method may be either electrical (the most common) or hydraulic. Automatic valves are commonly used as "control valves" for irrigation systems.

Available capacity (or available soil moisture)
The amount of water held in the soil that is available to the plants.

Available water-holding capacity (AWHC)
The amount of moisture plants can store in the root zone, usually expressed as a depth of water in inches or feet.

Backflow prevention device
A safety device used to prevent reverse flow of water back into a potable water supply line; typically used in conjunction with automatic irrigation systems.

Ball valve
A type of valve that controls the water by means of a rotating ball with a hole through the center of it. When the hole is aligned with the water flow the water flows freely through the valve with almost no friction loss. When the ball is rotated so that the hole is not aligned the flow is completely shut off.

Baseline
An established value or trend used for comparison when conditions are altered.

Benefit-cost ratio
Benefits and costs measured in terms of money and expressed as a ration, with benefits divided by costs; typically used as an evaluation tool for different water efficiency measures and programs.

Best management practice (BMP)
A set of practices, measures or procedures that are beneficial, empirically proven, cost effective, and widely accepted by the professional community.

Block-rate pricing
A method of charging for water based on the volume used. As more water is used, the price increases (or decreases) through a series of blocks. These pricing structures are designed to encourage efficient use of a resource.

Bluegrass
A variety of cool-season turf grass; also a style of folk music.

Booster pump
A device to increase the water pressure is a system where some pressure already exists. For example, if water comes from a water company at 40 PSI of pressure but you need 80 PSI of pressure for an irrigation system, you would use a booster pump to increase the pressure.

Bubbler
A type of sprinkler head that delivers water a level area where the water slowly infiltrates to the soil. Typically used to irrigate shrubs and trees.

Budget (water budget)
An accounting of water use for a given activity or location over a fixed period of time.

Building footprint
The area covered by a building as represented in a two-dimensional plan.

Bushing
A small piece used to connect two pipes of different sizes together. A standard reducer bushing has one male end (for the larger pipe) and one female connection (for the smaller pipe).

Butterfly valves
A type of valve that uses a rotating disk to control the water flow. A true butterfly valve has two half-disks, hinged together in the center. When the disks or "wings" are folded together the water flows freely past them. When folded out into the water stream the wings block the flow. Most "butterfly valves" are really "rotating disk" valves. They are mostly used on larger pipe sizes, seldom less than 3" in size. Ball valves are used on smaller size pipes.

Catch-can test
A measurement of precipitation from a sprinkler system in which water is collected in graduated containers (catch-cans) placed at evenly spaced intervals for a specific period of time.

CCF
100 cubic feet of water an amount equivalent to 748 gallons.

Central irrigation control
A computerized system that programs sprinkler clocks from a centralized location using a compute

Check valve
A device that prevents drainage of water from the low points of an irrigation circuit after irrigation stops.

Cistern
A tank (often underground) use to store water (often rainwater or graywater).

Closed loop cooling tower
Water-conserving cooling tower system in which water used for cooling is recycled through a piping system that cools the water; the water is cooled as air exchanges heat with the pipes.

Conservation
Increasing the efficiency of energy use, water use, production, or distribution; the act of conserving or preserving from injury or loss; the protection of rivers, forests and other natural resources.

Conservation pricing
Water rate structures that increase the price of water as more water is used with the goal of encouraging more efficient use.

Consumptive use (evapotranspiration)
Combined amounts of water needed for transpiration by vegetation and for evaporation from adjacent soil, snow, or intercepted precipitation. Also called crop requirement, crop irrigation requirement, consumptive use requirement.

Continuous flow system
The continuous use, by an industry, of deionized water to remove contaminants from products and equipment.

Continuous-flow irrigation
System of irrigation water delivery where each irrigator receives his allotted quantity of water at a continuous rate.

Cool-season grass
Turf grass varieties that are typically not damaged by sub-freezing temperatures. Includes bluegrass, Kentucky bluegrass, perennial rye grass, red fescue, and tall fescue.

Cooling tower
Water-conserving cooling device in which cooling water loses heat when a portion of it is evaporated.

Cooling tower makeup
Water added to the recirculating cooling tower water stream to compensate for water evaporation losses.

Cooling water
Water typically used to cool heat-generating equipment or to condense gases in a thermodynamic cycle.

Cooling water blowdown
Procedure used to reduce total dissolved solids by removing a portion of poor-quality recirculating water.

Cooling water evaporation
Cooling water recycling approach in which water loses heat when a portion of it is evaporated.

Coring
The mechanical cultivation of turf grass using hollow tines to remove cores of turf for the purpose of improving soil texture and increasing air and water circulation. Also called aeration.

Cost-beneficial
When the benefits are equal to or greater than the costs.

Cost-effectiveness
A comparison of total benefits against total costs.

Cubic feet per second (cfs)
A rate of flow; the volume, in cubic feet, of water passing a reference point in 1 second.

Cubic foot
A measurement of water equal to 7.48 gallons.

Decreasing block rate
Pricing that reflects per-unit costs of production and delivery that go down as customers consume more water.

Deep percolation
The movement of water by gravity downward through the soil profile beyond the root zone; plants do not use this water.

Demand forecast
A projection of future water use.

Demand management
The practice of systematically reducing water use for a broad spectrum of utility customers through efficiency measures and conservation, often as an alternative to purchasing new water or expanding water treatment facilities.

Demand scheduling
Method of irrigation scheduling whereby water is delivered to users as needed and which may vary in flow rate, frequency and duration. Considered a flexible form of scheduling.

Desalination
A process that converts seawater to freshwater through the removal of mineral salts and other dissolved solids.

Design Pressure
The total pressure available to operate an irrigation system.

Distribution efficiency
Measure of the uniformity of irrigation water distribution over a field.

Distribution system
A system of pipes and valves that conveys water from a treatment plant to end users.

Ditch
A constructed open channel for conducting water.

Diversion (structure)
Channel constructed across the slope for the purpose of intercepting surface runoff; changing the accustomed course of all or part of a stream.

Diversion (water)
Removal of water from its natural channels for human use.

Drainage
The process of removing surface or subsurface water from a soil or area.

Draw Down
The depth (from the top of the well) to the water in a well when the pump is operating. The water level typically drops when the pump is running.

Drip irrigation
A type of micro-irrigation systems that delivers water is slow drips to plants through a network of plastic pipes and emitters.

Drought
Climatic condition in which there is insufficient soil moisture available for normal vegetative growth for an extended period of time.

Drought condition
The hydrologic conditions during a defined drought period in which rainfall and runoff are much less than average.

Dual-flush toilet
A toilet designed to use a lower volume of water to flush liquid wastes and a higher volume of water to flush solid wastes.

Early closure flapper
A toilet flapper valve that closes sooner than normal to reduce the volume of water flushed.

Effective precipitation
The total depth of rainfall minus the volume lost to evaporation and leaching during a specific time period.

Efficiency
The use of a resource that maximizes the benefit and minimizes consumption of the resource.

Effluent
Wastewater, treated or untreated, that flows out of a treatment plant, sewer, or industrial outfall.

Elevation head
A measurement of pressure.

Emitter
A drip irrigation system fitting that delivers water to plants at a slow and predictable rate.

End use
Fixtures, appliances, plumbing devices, equipment, and activities that use water.

End user
A consumer of water; a utility water customer.

Energy Policy Act (1992)
A federal law enacted by President George Bush that established maximum allowable water-use requirements for toilets, urinals, showerheads, and faucets manufactured and sold in the United States.

Environment
The sum of all external influences and conditions affecting the life and development of an organism or ecological community.

Erosion
A gradual wearing away of soil or rock by running water, waves, or wind.

Established landscape
A landscape that has been in place for an extended period of time where the roots of the plants are well developed.

Evaporation
The process by which water changes from liquid to vapor.

Evapotranspiration (ET)
Water lost from the surface of soils and plants through the processes of evaporation and transpiration combined.

Evapotranspiration (ET) rate
A measure of the amount of water required to maximize plant growth. This measure is calculated from climatic conditions and factors such as temperature, solar radiation, humidity, wind, time of year, precipitation, etc.

Fallow
Land plowed and tilled and left unplanted.

Faucet aerator
A device that can be installed in a sink to reduce water flow rate by adding air to the water.

Faucet restrictor
A device inserted into a faucet that forces water through a smaller orifice for the purpose of reducing the flow rate.

Field capacity
The depth of water retained in the soil after ample irrigation or heavy rain when the rate of downward movement has substantially decreased, usually one to three days after irrigation or rain, expressed as a depth of water in inches or feet. Also called field moisture capacity.

Fixed charge
The portion of a water bill that does not vary with water use.

Fixed costs
Costs for a utility that do not vary with the amount of water produced, delivered, and sold to customers.

Flat rate
A fee structure in which the price of water is constant regardless of the amount consumed.

Flood irrigation
A method of irrigating where water is applied from field ditches onto land that has no guide preparation such as furrows, borders or corrugations.

Floodplain
The land adjacent to a river or stream that is subject to flooding.

Flow rate
The amount of water moving through a pipe, fixture, stream, etc. Often measured in gallons per minute.

Flow restrictor
A washer-like disk that fits inside a faucet or showerhead and reduces the water flow rate.

Flushometer toilet
A tankless toilet with the flush valve attached to a pressurized water supply pipe. These toilets are typically found in large institutional and commercial buildings such as schools, airports, office buildings, etc.

Freshwater
Water that contains relative low mineral content as opposed to seawater or salt water.

Gage
Device for registering water level, discharge, velocity, pressure, etc.

Gage height
Elevation of water surface measured by a gage.

Gate (irrigation)
Structure or device for controlling the rate of flow into or from a canal or ditch.

Gated pipe
Portable pipe with small gates installed along one side for distributing irrigation water to corrugations or furrows.

Gauging station
Specific location on a stream where systematic observations of hydrologic data are obtained through mechanical or electrical means.

gpc
Gallons per cycles

gpcd
Gallons per capita per day

gpd
Gallons per day

gpf
Gallons per flush

gph
Gallons per hour

gphd
Gallons per household per day

gpl
Gallons per load (of laundry or dishes)

gpm
Gallons per minute

gpy
Gallons per year

Gravity flow
A water system that relies on gravity to provide the pressure required to deliver the water. Consists of a water source located at a higher elevation than the water delivery points.

Gravity-flush toilet
The standard tank style of toilet that uses water (at standard gravitational pressure) to perform flushing functions.

Graywater
Domestic wastewater composed of wash water from kitchen sinks, bathroom sinks and tubs, clothes washers, and laundry tubs that can be used for non-potable purposes such as irrigation.

Green industry
The industry that includes design, maintenance, installation, and management of landscapes.

Groundwater
Water beneath the earth's surface.

Groundwater mining (overdraft)
Pumping of groundwater for irrigation or other uses, at rates faster than the rate at which the groundwater is being recharged.

Groundwater recharge
The flow to groundwater storage from precipitation, infiltration from streams, and other sources of water; the use of reclaimed wastewater, by surface spreading or direct injection, to prevent saltwater intrusion into freshwater aquifers, to store the reclaimed water for future use, to control or prevent ground subsidence, and to augment non-potable or potable ground water aquifers.

Groundwater table
The upper boundary of groundwater where water pressure is equal to atmospheric pressure, i.e., water level in a bore hole after equilibrium when groundwater can freely enter the hole from the sides and bottom.

Growing season
The period, often the frost-free period, during which the climate is such that crops can be produced.

Hardscape
Landscaped areas covered by non-living materials such as concrete, bricks, rocks, wood, pavement, etc.

High-water-use landscape
A landscape made up of plants, turf and features that requires 50 to 80% of the reference evapotranspiration to maintain optimal appearance.

Horticultural practices
Activities to maintain plants and landscapes such a s fertilization, mowing, and thatch control.

Hydrology
Science dealing with the properties, distribution, and flow of water on or in the earth.

Hydrozone
A portion of a landscaped area comprising plants with similar water requirements.

Increasing block rate
Pricing that reduces water use by structuring water rates to increase per-unit charges as the amount used increases.

Incremental cost
The additional cost associated with adding a specific amount (increment) of capacity to a water supply.

Infiltration rate
The rate of water entry into the soil expressed as a depth of water per unit of time in inches per hour or feet per day. The infiltration rate changes with time during irrigation.

Instream flow
Water flows for use within a defined stream channel e.g., flows intended for fish and wildlife.

Integrated resource planning
A planning process emphasizing least-cost principles and balanced consideration of supply and demand management options for meeting water needs.

Invasive plant
A non-indigenous plant that invades and takes over substantial areas of an ecosystem.

Investor-owned utility
A privately owned utility usually regulated by a state public utility commission.

Irrigated acreage
Irrigable area actually irrigated in any one year.

Irrigation
Application of water to lands for the purpose of growing plants.

Irrigation audit
An on-site evaluation of an irrigation system to assess its water-use efficiency as measured by distribution uniformity, irrigation schedule, and other factors.

Irrigation controller
A sprinkler clock or timer.

Irrigation cycle
A scheduled application of water by an irrigation system with a defined start time and duration. A cycle may include multiple watering zones.

Irrigation districts
Special units of local government that control the bulk of surface water supplies in the western United States.

Irrigation efficiency
The ratio of the average depth of irrigation water that is beneficially used to the average depth of irrigation water applied, expressed as a percent. Beneficial uses include satisfying the soil water deficit and any leaching requirement to remove salts from the root zone.

Irrigation plan
A 2-D drawing/plan that illustrates the layout of an irrigation system.

Irrigation requirement
Quantity of water, exclusive of effective precipitation, that is required for maintaining a landscape.

Irrigation scheduling
Careful choice of irrigation application rates and timing to help irrigators maintain yields with less water.

Irrigation timer
A device that can be programmed to regulate the time and duration of irrigation; a sprinkler clock.

Irrigation water requirement
A measure of the water required in addition to precipitation to obtain desired crop yield.

Isolation valve
A valve used for isolating all or part of an irrigation system for repairs, maintenance, or winter shut-down (winterization). Common types of isolation valves are the ball valve, butterfly valve, and gate valve.

Kilowatt-hour (kWh)
A unit of electric power equivalent to the energy provided by one thousand watts acting for one hour.

Landscape area
The total area on a property that contains landscaping elements. Usually equivalent to the total area minus the building footprint and paved driveways and paths.

Landscape water requirement
A measure of the supplemental water required to maintain the optimum health and appearance of landscape plants and features.

Leaching
Removal of soluble material from soil or other permeable material by the passage of water through it.

Leaching requirement
Quantity of irrigation water required for transporting salts through the soil profile to maintain a favorable salt balance in the root zone for plant development.

Leak detection
Systematic methods for identifying water leakage from pipes, plumbing fixtures, and fittings.

Lifeline rate
A minimum, sometimes subsidized water rate created to help meet basic human needs.

Low-flow faucet
A faucet that uses no more than 2.5 gallons per minute at 80 pounds of pressure per square inch.

Low-flow plumbing
Plumbing equipment that uses less water than was considered standard prior to January 1, 1994.

Low-flow showerhead
A showerhead that requires 2.5 gallons of water per minute or less.

Low-flush toilet
A toilet that requires 1.6 gallons of water per flush or less.

Low-volume urinal
A urinal that uses no more than 1.0 gallons per flush.

Low-water-use landscape
Use of plants that are appropriate to an area's climate and growing conditions.

Low-water-use plants
Plants that require less than 30% of reference ET to maintain optimum health and appearance.

Lysimeter
An isolated block of soil, usually undisturbed and in situ, for measuring the quantity, quality, or rate of water movement through or from the soil.

Main
The pressurized water delivery pipeline that delivers water from the supply system to the customer's service line.

Marginal-cost pricing
A rate design method where prices reflect the costs associated with producing the next increment of supply.

Market penetration
The extent to which a water efficiency measure is actually implemented.

Matched precipitation rate
An equal rate of water delivery from sprinkler heads with varying arc patterns within an irrigation circuit. Matched precipitation rates are central to achieving uniform distribution or irrigation water.

Medium-water-use plants
Plants that require 30 to 50 percent of reference ET to maintain optimum health and appearance.

Megawatt
One million watts; a measure of power plant output.

Meter
An instrument that measures the volume of water use.

Metering
Use of metering equipment that can provide essential data for charging fees based on actual customer use.

mgd
Million gallons per day.

mgy
Million gallons per year.

Micro-irrigation
An irrigation system with small, closely spaced outlets used to apply small amounts of water at low pressure.

Microclimate
The climate conditions of a specific habitat or place in a small, limited area.

MOU
Memorandum of understanding.

Mulch
A covering placed around plants to minimize weed growth and reduce evaporation. Typically leaves, bark, wood chips, straw, compost, or other organic materials.

Multiple start times
An irrigation schedule where the system is programmed to start and run several times during the day.

Native landscape
A landscape that features plants and grasses indigenous to the region.

Native plants
Plants that are indigenous to a region and require litter or no supplemental irrigation after establishment.

Natural landscape
A landscape created to reflect the character and spirit of nature and the native surroundings.

Net present value
The present value of benefits minus the present value of costs.

Neutron probe
An instrument used to estimate soil moisture. Relates the rate of attenuation in pulsed neutron emissions to soil water content.

Non-residential water use
Water use by industrial, commercial, institutional, public, and agricultural users.

Nonconsumptive water use
Water withdrawn for use but not consumed and thus returned to the source.

Operating pressure
The pressure at which a device or irrigation system is designed to operate.

Ozonation
The process of applying to a liquid for disinfection.

Pan evaporation
Evaporative water losses from a standardized pan. Pan evaporation is sometimes used to estimate crop evapotranspiration and assist in irrigation scheduling.

Peak demand
The highest total water use experienced by a water system.

Peak/off-peak rates
Rates charged in accordance with the most and least popular hours of water use during the day.

Per capita use
The amount of water used by one person during one 24 hour period. Typically expressed as gallons per capita per day (gpcd).

Percolation
Downward movement of water through the soil profile or other porous media.

Percolation rate
(1) The rate at which water moves through porous media, such as soil; and (2) Intake rate used for designing wastewater absorption systems.

Permanent wilting point
Soil water content below which plants cannot readily obtain water and permanently wilt. Sometimes called "permanent wilting percentage.

Plant water requirement
The amount of irrigation water needed to replace moisture depleted from the soil around plant roots as a result of evapotranspiration.

Point source
A specific site from which waste or polluted water is discharged.

Pop-up sprinkler head
A sprinkler head that retracts below ground level when it is not operating.

Potable water
Water that is safe for drinking.

Pounds per square inch (psi)
A standard measure of water pressure.

Precipitation rate
The amount of water applied by a sprinkler system in a specific unit of time.

Present value
Future expenditures expressed in current dollars by adjusting for a discount rate that accounts for financing costs.

Pressure gauge
A device used to measure water pressure. The best pressure gauges are "liquid filled", however most cheap gauges work well enough for irrigation system use.

Pressure loss
Loss in water pressure caused by friction of water against the inner walls of pipe or system components.

Pressure reducer
A component designed to reduce water pressure in supply system pipe or irrigation lines.

Pressure regulator
A device used to limit water pressure.

Pressurized-tank toilet
A toilet that flushes by using pressure from the waterline entering a pressurized plastic vessel inside the tank.

Price elasticity of demand
A measure of the responsiveness of customer water use to changes in the price of water; measured by the percentage change in price.

Price gouging
Excessive water rate increases that are unfair to water customers.

Pricing signals
Rate structures that encourage water conservation by customers.

Pricing/rate structure
System used by water utility managers to charge customers for water usage.

Rain sensor
A device that automatically shuts off an irrigation system after a set amount of precipitation falls.

Rain switch
A simple on/off switch on an irrigation system that makes it easy to shut the system down during a rainstorm.

Rainwater harvesting
The capture and use of runoff from rainfall.

Rationing
Mandatory water use restrictions typically imposed during a drought.

Recharge
The addition of water to the groundwater supply by natural or artificial means.

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

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

Recycled water
A type of reuse water usually run repeatedly through a closed system; sometimes used to describe reclaimed water.

Reference evapotranspiration (ETÂș)
The evapotranspiration of a broad expanse of adequately watered cool-season grass 4 to 6 inches in height. A standard measurement for determining maximum water allowances for plants so that regional differences in climate can be accommodated.

Reservoir
A body of water, such as a natural or constructed lake, in which water is collected and stored for use.

Residential End Uses of Water Study (REUWS)
The Residential End Uses of Water study published by the American Water Works Association Research Foundation in 1999.

Residential water use
Water use in homes and apartments.

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

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

Return flow
That portion of the water diverted from a stream that finds its way back to the stream channel, either as surface or underground flow.

Reverse osmosis
Common process used to produce deionized water from municipal water.

Riparian
Of, on, or pertaining to the bank of a river, pond, or lake.

Riser
The connection between a sprinkler or other irrigation device and the pipe that supplies the water to it.

Root zone
That depth of soil which plant roots readily penetrate and in which the predominant root activity occurs.

Runoff
The portion of precipitation, snow melt, or irrigation that flows over the soil, eventually making its way to surface water supplies.