Providing clean, affordable, public water since 1939!

Chester City Location

415 Welsh Street
Chester, PA 19013

Kennett Square Location

148 West State Street, Suite 101
Kennett Square, PA 19348

Open Hours

Mon – Fri : 8:30AM – 4:30PM
No Walk-ins • Appt Only
24/7 for Emergency: 610-876-8181


understanding water terminology


Below is a list of water terms with accompanying definitions.

Acre Foot – A volume of water equal to one foot in depth covering an area of one acre, or 43,560 cubic feet; approximately 325,851 gallons. Roughly two-thirds of an acre foot serves the needs of a typical family of four for a year.

Allocation – The right to take water from a natural stream or aquifer for beneficial use at a specified rate of flow, either for immediate use or to store for later use. Water Allocation Permits are issued in Pennsylvania by the Pennsylvania Department of Environmental Protection.

Alluvial Water – Water that is hydrologically part of a natural surface stream system.

American Academy of Environmental Engineers – A professional association that encourages excellence in environmental engineering and provides certification for qualified environmental engineers.

American Public Works Association – An association representing the public works profession.

American Water Works Association (AWWA) – The largest association in the world serving drinking water professionals and dedicated to the provision of safe drinking water.

Aqueduct – man-made canal or pipeline used to transport water.

Aquifer – An underground layer of sand, gravel, or rock through which water can pass and is stored. Aquifers supply the water for wells and springs. They may be alluvial or nontributary in nature.

Association of Boards of Certification – Promotes water and wastewater operator certification through model state legislation and national testing services.

Association of Metropolitan Water Agencies – An association representing large municipal public water agencies.

Association of State Drinking Water Administrators – An association representing state drinking water regulatory agencies.

Automated Meter Reading (AMR) – With this special water meter installed in homes and businesses, CWA vans equipped with a computer communicates by radio waves to determine water usage. The van drives down local streets requiring no access to buildings. The van sends digital information directly to a computer, resulting in accurate (not estimated) bills.

BMPs(Best Management Practices) – Structural or management practices that are implemented to encourage the best possible use of water resources.

Backflow Prevention – Prevention of the flow of any foreign liquids, gases, or substances into the distribution pipelines of a potable water supply; accomplished by an air gap or mechanical backflow obstacle.

Beneficial Use – Lawful and prudent use of water that has been diverted from a stream or aquifer for human or natural benefit.

Brackish Water – Water that is slightly salty.

Bypass Flow – Water that is allowed to flow past a diversion structure or storage facility.

Capital Costs – Costs associated with the purchase of, or improvements to tanks, treatment plants, etc.

Chlorine – Chemical used in the water treatment process as a disinfectant. Chlorine is used to assure the bacterial safety of the drinking water and to improve its quality.

Chloramination – The treatment of a substance, such as drinking water, with chlorine and ammonia (chloramines) in order to kill disease-causing organisms.

Clean Water Act – The federal law that establishes how the United States will restore and maintain the chemical, physical and biological integrity of the country’s waters (oceans, lakes, streams and rivers, ground water and wetlands). The law provides protection for the country’s waters from both point and non-point sources of pollution.

Cleaning and Lining – Clean out old unlined cast iron pipes and reline with concrete for longer usage, to prevent leakage, and increase flows.

Coliform – A bacteria that may originate in the environment or in the digestive system of mammals. If found in water, it alerts lab technicians that pathogens might be present.

Cumulative Impact Analysis – A review of the cumulative environmental, social and economic impacts of proposed water projects and activities associated with development within an ecosystem or drainage area.

Condensation – Water vapor changing back into liquid.

Conjunctive Use – Coordinated use of surface and ground water supplies to meet demand so that both sources are used more efficiently.

Conservation – Obtaining the benefits of water more efficiently, resulting in reduced demand for water. Sometimes called “end-use efficiency” or “demand management.”

Consumption Pattern – The variation in the amount of water a customer uses over time.

Cubic Feet Per Second (CFS) – A rate of flow of water passing a given point, mounting to a volume of one cubic foot for each second of time. Equal to 7.48 gallons per second, 448.8 gallons per minute, or 1.984 acre feet per day.

Cumulative Impact Analysis – A review of the cumulative environmental, social and economic impacts of proposed water projects and activities associated with development within an ecosystem or drainage area.

Customer Information System (CIS) – Customers contact or are contacted by CWA, approximately 3,000 times a month. CIS maintains up-to-date information on service, account records, and meter information. Data on water mains, valves, hydrants, pumps, tanks, meters, and service lines is linked to the Customer Information Service to expedite new service and repairs.

Demand Forecast – A prediction of future water use. Most water demand forecasting models are either directly or indirectly based upon projected changes in demographic data, such as population, etc.

Demand Management – Reductions of water usage, accomplished either through temporary measures such as restrictions during a drought, or through long-term conservation programs. These include replacement of inefficient fixtures with more efficient fixtures such as 1.6 gallon toilets, installation and maintenance of landscapes that have low water requirements, or through changes in customer attitudes toward water conservation, leading to reduction in water use.

Desalination – The process of removing salt from seawater or brackish water.

Disinfect – To destroy harmful microorganisms.

Disinfection By-Product – Organic or inorganic by-products of disinfection.

Diversion – The removal of water from its natural course or location, or controlling water in its natural course or location, by means of a ditch, canal, flume, reservoir, bypass, pipeline, conduit, well, pump, or other device.

Drought – A long period of below-average precipitation.

Effluent – The water leaving a water or wastewater treatment plant.

Environmental Impacts – Factors that affect organisms and the surroundings of organisms.

Escherichia Coli (e. coli) – A bacterium that is a primary indictor of fecal contamination in a water supply. E. coli is a member of the coliform group of bacteria.

Evaporation – Water changing into vapor and rising into the air.

Exchange – A process by which water, under certain conditions, may be diverted out of priority at one point by replacing a like amount of water at a downstream location.

Filtration – Passing water through beds of coal, sand, and gravel to remove particles.

Financial Information System (FIS) – Works closely with CIS to maintain and prepare accurate revenue and expenditure records.

Finished Water – Treated potable water that is considered safe and suitable for delivery to consumers.

Firm Annual Yield – The yearly amount of water that can be dependably supplied from the raw water sources of a given water supply system.

Fluoride – Approximately 0.7 parts per million of fluoride is added to the water. This is the amount recommended by the American Dental Association to provide maximum dental protection.

Gallons Per Account Per Day (GAD) – A term generally used to approximate the average amount of water used by a customer account on a daily basis. The formula used to determine GAD is: Total Treated Water Delivered (over a year) divided by Total Accounts of Water Service Area (customers) divided by 365 days/year = Gallons Per Account Per Day.

Gallons Per Capita Per Day (GCD) – A term generally used to approximate the average amount of water used per day, per person, over a period of one year. It is generally compiled only on a systemwide basis. The formula used to determine GCD is: Total Treated Water Delivered (over a year) divided by Total Population of Water Service Area divided by 365 days/year = Gallons Per Capita Per Day.

Gas Chromatograph/Mass Spectrometer – A specific type of instrument used to detect and quantify organic compounds.

Giardia Lamblia – Microscopic protozoa which, when ingested, can result in diarrhea and other flu-like symptoms.

Granular Activated Carbon – A specially produced carbon with a high adsorption capacity used to remove a wide range of organic compounds.

Ground Water – Water found below the surface of the Earth.

Hardness – Hardness defines the quantity of minerals such as calcium and magnesium in a gallon of water. These minerals react with soap to form insoluble precipitates and can affect common household chores such as cooking and washing. Hardness also affects other water qualities such as its corrosiveness, with soft water being more corrosive. CWA water is considered medium hard.

Hydrologic Cycle – The movement of water from the atmosphere to the Earth and back again to the atmosphere. The three stages are precipitation, runoff or infiltration, and evaporation.

Inorganic Chemical – Chemical substance of mineral origin not having carbon in its molecular structure.

Irrigation District – The main purpose of an irrigation district is to develop, preserve and conserve water for beneficial use of those living within the area.

Land Use – Land use alongside our rivers includes farms, parking lots, and housing. When it rains on this land, fertilizers, pesticide, oil, grease, and other pollutants run off into the water. Our water requires a good deal of treatment before it is safe to drink.

Maximum Contaminant Level – The highest permissible concentration of a substance allowed in drinking water, as established by US Environmental Protection Agency (EPA).

Maximum Contaminant Level Goal – The highest permissible concentration of a substance allowed in drinking water at which no known or anticipated health effects will occur. They are health goals and are not enforceable. They replaced the Recommended Maximum Contaminant Level when the Safe Drinking Water Act was amended in 1986.

mg/L – Milligrams per liter; a measurement describing the amount of a substance (such as a mineral, chemical, or contaminant) in a liter of water. One milligram per liter is equal to one part per million.

Microorganism – An organism of microscopic size, such as bacterium.

Million Gallons Per Day (mgd) – Unit of measure to quantify the water usage and capacity.


National Drinking Water Week – The annual drinking water public awareness campaign held the first full week of May.

National Water Alliance – A group of Congressional members and other interested people that influences national policies and educates the public regarding water supply.

Natural Replacement – The ordinary replacement of older, less efficient water fixtures (toilets, faucets, etc.) with new, more efficient fixtures as the older fixtures wear out, break, or are replaced.

Net Demand – The water demand that is expected to occur in the future after reductions for natural replacement and conservation. It represents the actual demand that should be experienced in the future at customers’ premises. Usually expressed in thousand acre feet (KAF).

Non-Consumptive Use – Water drawn for use that is not consumed, such as water diverted for hydroelectric generation. It also includes such uses as boating and fishing, where water is still available for other uses at the same site.

Non-Point Source – The source of pollution discharged over a wide land area, not from any specific area, that finds its way into streams, lakes, and oceans, such as runoff from streets, parking lots, lawns, agricultural land, individual septic systems, and construction sites.

Non-Tributary Ground Water – Underground water in an aquifer that neither draws from nor contributes to a natural surface stream in any measurable degree.

NTU (Nephlometric Turbidity Unit) – A measure of clarity.


Operating Costs – Costs associated with operation and maintenance (i.e., equipment repairs, salaries, etc.).


Participation Agreement – An agreement in which a distributor or developer pays for the cost of the distribution facilities such as conduits, treated water reservoirs, or pump stations required to provide service within that district from the nearest existing available source.

Parts Per Billion – One in a billion. For water, one gallon in a billion gallons of water. One thousand parts per billion is equal to one part per million.

Parts Per Million – One in a million. One gallon in a million gallons of water.

Percolation – Water soaking into the ground.

pH – Relative scale of how acidic or basic (alkaline) a material is; the scale goes from 0 to 14. The value of 7 is neutral, acids have pH values less than 7 and bases have pH values higher than 7.

Point-of-Entry Devices – A home-water treatment unit that treats water for an entire house or building.

Point-of-Use Devices – A home-water treatment unit that treats water from only one tap.

Point Source – The source of pollution discharged from any identifiable point, including ditches, channels, sewers, tunnels, and containers of various types.

Potable – Water that does not contain pollution, contamination, objectionable minerals, or infective agents and is considered safe for domestic consumption; drinkable.

Powdered Activated Carbon – A finely ground form of activated carbon that is added directly to water as a slurry for removal of organic compounds.

Pressure Pipe – Pipe used to distribute potable water throughout the city for fire fighting and domestic purposes.

Pressure Regulating Valve (PRV) – A device that takes pressure from a high zone through a valve and regulates it to a zone of lower pressure.

Pressure Zone – Geographical area within a water distribution system defined by a number of valves with at least two feeds.

Projected Savings – An estimate of the amount of water that will not be used because both suppliers and customers are implementing certain efficiency practices.


Rated Capacity – The volume of water a treatment plant is capable of producing under normal operating conditions.

Raw Water – Untreated water.

Reservoir – A body of water used to collect and store water, or a tank or cistern used to store potable water.

Retrofit – An umbrella term that refers to the modification of something for more efficiency. In the case of water conservation, retrofit refers to modifications to plumbing fixtures to increase efficiency.

Reuse – To use again; recycle; to intercept, either directly or by exchange, water that would otherwise return to the stream system, for subsequent beneficial use.

Reverse Osmosis – A water treatment technique that forces water through a dense membrane to remove impurities.

Riparian Rights – Water rights that are acquired together with title to the land bordering a source of surface water; the right to put to beneficial use surface water adjacent to one’s land.

Run-Off – Water that flows on the surface of the Earth into streams, rivers, lakes and oceans.


Safe Drinking Water Act – The federal law that authorizes US Environmental Protection Agency to establish national drinking water regulations. Originally enacted in 1974, the Act was extensively amended in 1986.

Safety Factor – An amount of water added to demand projections to protect against unforeseen changes in water supply and demand.

Sludge – A semi-liquid mass of accumulated settled solids deposited from the treatment plant process. Settled solids from CWA’s treatment process are dried and used in compost.

Spill Water – Water released from a reservoir because the reservoir lacks sufficient storage capacity.

Storage – Water held in a reservoir for later use.

Supply Management – Methods by which a utility maximizes use of available untreated water.

Surface Water – Water located on the Earth’s surface.

Sustainability – A decision-making concept describing development that meets the needs of the present without compromising the ability of future generations to meet their own needs.

Synthetic Organic Chemical – Man-made organic chemicals, many of which have been detected in drinking water. This group includes VOCs (Volatile Organic Chemicals).

System Loss – An amount of water, expressed as a percentage, lost to leaks, seepage, and unauthorized use.


Tap – A physical connection made to a public water distribution system that provides service to an individual customer.

Transpiration – Evaporation of water through the leaves of plants.

Treated Water – Water that has been filtered and disinfected. Term is sometimes used interchangeably with potable water.

Tributary – A stream or river that flows into a larger one.

Tributary Drainage – The area from which water drains by gravity into a water course.

Tributary Ground Water – Water below the Earth’s surface that is physically or hydrologically connected to natural stream water so as to affect its flow whether in movement to or from that stream.

Trihalomethane – A group of volatile organic compounds formed when chlorine reacts with naturally occurring humic substances.

Total Trihalomethanes – A term used to designate the total concentration of chloroform, bromoform, dibromochloromethane, and bromodichloromethane.

Turbidity – Sediment or particles suspended or floating in water.


Unaccounted-For Water – The difference between the total amount of water leaving treatment facilities and the total amount of water measured at customers’ meters. Besides system losses, it also includes beneficial uses such as unmetered fire fighting and water used in system maintenance, along with meter under-registration.

Unconstrained Demand – The demand that would be experienced were it not for conservation and natural replacement. Usually expressed in thousand acre feet (KAF).

Urban Runoff – Water from an urban area that neither infiltrates the soil nor is consumed, but flows into a storm sewer or open waterway.

US Environmental Protection Agency (USEPA) – The federal agency created in 1970 that implements major environmental legislation.


Valve – Mechanical device for controlling or stopping flow of water in a pipe.

Volatile Organic Chemical – Lightweight organic compounds that vaporize or evaporate easily.


Water Distribution Management System (WDMS) – This system gathers data on water mains, valves, hydrant, pumps, tanks, meters and service lines. The information gathered through WDMS is now being integrated with CIS.

Water Main (or Distribution Main) – A 12-inch or smaller diameter pipe along public streets or appropriate rights-of-way used for distributing water to individual customers.

Water Right – A property right to make beneficial use of a particular amount of water with a specified priority date.

Watershed – An area from which water drains and contributes to a given point on a stream or river (Octoraro Watershed).

Water Wiser – The Water Efficiency Clearinghouse. A source of information in print and/or electronic media accessible by phone, fax, or Internet sponsored by the American Water Works Association (AWWA) and the US Environmental Protection Agency (EPA). This information can be accessed by calling 1-800-559-9855.

Wetlands – Areas with standing water or a high water table that under normal circumstances support vegetation typically adapted to saturated soil conditions; generally includes swamps, marshes, bogs, and areas with vegetation that grows in or around water.


Xeriscape – Landscaping concept that requires less water on vegetation that is suited to soils and climate. It is derived from the Greek word Xeros, meaning dry.

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Phone Payment System


Pay your water bill or obtain your account balance and due date by telephone 24 hours a day, 7 days a week. Our automated phone payment system accepts Visa, MasterCard and e-checks.

The vendor charges a $2.75 convenience fee to process a payment.

Paying your bill is as EASY as 1,2,3,…….

  1. 1. Enter your Customer Number
  2. 2. Enter your Account Number
  3. 3. Enter your payment information.
Open Hours:
Mon – Fri
8:30AM – 4:30PM
No Walk-ins • Appt Only

24/7 for Emergency: