Acre-foot

This unit of measurement is used in the water industry to describe large quantities of water, such as the capacity of a reservoir. One acre-foot equals approximately 326,000 gallons, or enough water to cover one acre of land (about the size of a football field) one foot deep in water. One acre-foot of water is enough to meet the needs of an average family for two years.

Activated Sludge

The biological process that removes organic matter from wastewater using microscopic plants and animals (organisms). The activated sludge process imitates the natural process that a river, lake or stream uses to clean itself.

Advanced Treatment

Additional treatment processes used to clean wastewater even further following primary and secondary treatment. Also known as tertiary treatment.

Aeration Tank

A chamber in which air is injected into wastewater to allow microscopic organisms to clean the water (see Activated Sludge).

Algae

The simplest kind of green plants, usually found growing in damp or wet places.

Aqueduct

A constructed system of canals, channels and/or pipelines to move water from one location to another.

Aquifer

Underground rock, sand or gravel formations which store water.

Arid

Dry; deserts are arid places. Semi-arid refers to a place that is almost as dry as a desert.

Biosolids

The solids, or sludge, that remain after wastewater treatment. This material is separated from the cleaned water, treated and composted into fertilizer. Biosolids are often referred to as sludge.

Canal

A ditch used to move water from one location to another.

Clarify

To make clear or pure by separation and elimination of suspended solid material.

Coagulation

The clumping together of solids so they can more easily be settled out or filtered out of water. A chemical called aluminum sulfate (alum) is generally used to aid coagulation in water treatment and reclamation.

Condensation

The process of water vapor (gas) changing into liquid water. An example of condensation can be seen in the tiny water droplets that form on the outside of a glass of iced tea as warmer air touches the cooler glass.

Contaminate

To make unclean or impure by the addition of harmful substances.

Dam

A barrier built across a river or stream to hold water.

Decompose

To separate into simpler compounds, substances or elements.

Desalination

Refers to any of several processes that remove excess salt and other minerals from water.

Dilute

To lessen the amount of a substance in water by adding more water.

Disinfect

To destroy disease-causing organisms in water.

Effluent

Treated water or wastewater exiting a treatment plant, or exiting a particular stage of the treatment process (i.e. primary effluent, secondary effluent, final effluent).

Evaporation

The process that changes water (liquid) into water vapor (gas).

Filtration

The process of allowing water to pass through layers of a porous material such as sand, gravel or charcoal to trap solid particles. Filtration occurs in nature when rain water soaks into the ground and it passes through hundreds of feet of sand and gravel. This same natural process of filtration is duplicated in water and wastewater treatment plants, generally using sand and coal as the filter media.

Greenbelt

An area of parks, landscaping or undeveloped natural land surrounding or within a community.

Groundwater

Water located beneath the Earth’s surface.

Household Hazardous Waste

Any product found in the home or garage that can be hazardous to the environment if not disposed of correctly. Examples of household hazardous waste include cleaning solutions, pesticides, pool chemicals, motor oil, antifreeze, or used batteries.

Hydrologic Cycle

Also called Water Cycle. The continuous process of surface water (puddles, lakes, oceans) evaporating from the sun’s heat to become water vapor (gas) in the atmosphere. Water condenses into clouds and then falls back to earth as rain or snow (precipitation). Some precipitation soaks into the ground (percolation) to replenish groundwater supplies in underground aquifers.

Influent

Water or wastewater entering a treatment plant, or a particular stage of the treatment process.

Irrigation

Applying water to crops, lawns or other plants using pumps, pipes, hoses, sprinklers, etc.

MAF

Million acre-feet.

Microbes

Microscopic living plants and animals.

Microorganism

An animal or plant of microscopic size.

Mulch

Any substance such as leaves, bark, compost or straw which is spread on the ground to protect roots of plants from heat, cold or excessive dryness.

Non-Point Source Pollution

Pollution that is so general or covers such a wide area that no single, localized source of the pollution can be identified.

Organism

Any living plant or animal.

Percolation

The movement of water through soil, sand, gravel, etc.

Point Source Pollution

An identifiable source of pollution.

Precipitation

Water from the atmosphere that falls to the ground as a liquid (rain) or a solid (snow, sleet, hail).

Primary Treatment

Removing solids and floating matter from wastewater using screening, skimming and sedimentation (settling by gravity).

Reservoir

A place where water is stored until it is needed. A reservoir can be an open lake or an enclosed storage tank.

Secondary Treatment

The biological portion of wastewater treatment which uses the activated sludge process to further clean wastewater after primary treatment.

Sedimentation

The settling of solids in a body of water using gravity.

Settle

To clarify water by causing impurities or solid material to sink to the bottom of the container.

Sewer

The system of pipes that carries wastewater from homes and businesses to a treatment plant or reclamation plant. Sewers are separate from storm drains, which is a system of drains and pipes that carry rain water from urban streets back to the ocean.

Sludge

The solids that remain after wastewater treatment. This material is separated from the cleaned water, treated and composted into fertilizer. Another word for sludge is biosolids.

Storm Drain

The system of pipes that carries rain water from urban streets back to the ocean. Overwatering your yard can also cause water to run into the streets and into storm drains. Storm drain water is not treated before it is discharged. Storm drains are separate from sewers, which is a separate system of pipes to carry wastewater from homes and businesses to a treatment plant or reclamation plant for cleaning.

Tertiary Treatment

Additional treatment processes used to clean wastewater even further following primary and secondary treatment. Also known as advanced treatment.

Transpiration

The process by which a plant gives off water into the atmosphere. This is part of the water cycle.

Wastewater

Used water that goes down the drains of homes and businesses.

Water Conservation

Using water wisely and efficiently so that it is not wasted.

Water Cycle

The continuous process of surface water (puddles, lakes, oceans) evaporating from the sun’s heat to become water vapor (gas) in the atmosphere. Water condenses into clouds and then falls back to earth as rain or snow (precipitation). Some precipitation soaks into the ground (percolation) to replenish groundwater supplies in underground aquifers.

Water Reclamation

The treatment of wastewater to make it suitable for a beneficial reuse, such as landscape irrigation. Also called water recycling.

Water Table

The top level of water stored underground.

Watershed

The lands above a given point on a waterway that contribute water run-off.

Wetland

Any area in which the water table stands near, at, or above the land surface for at least part of the year. Such areas are characterized by plants that are adapted to wet soil conditions.