Backflow
A reverse flow condition created by a difference in water pressures, which causes water to flow back into the distribution pipes of a potable water supply from any source or sources other than an intended source.

BTU
British Thermal Unit. A unit of measurement for energy, a measure of heat content or heating value. The energy required to raise the temperature of one pound of water by one degree farenheit, under standard pressure.

Clean Water Act
The common term for the Federal Water Pollution Control Act of 1972 (amendments passed in 1977, 1981, and 1994) which set standards for the "chemical", physical, and biological integrity of the nations' water".

CFS
A rate of the flow, in streams and rivers, for example. It is equal to a volume of water one foot high and one foot wide flowing a distance of one foot in one second. One "cfs" is equal to 7.48 gallons of water flowing each second.

CF
A cubic foot is a measurement of volume used to reference water consumption, equivalent to 7.485 gallons.

CCF
One hundred cubic feet. A measurement of natural gas volume that has a heating value of approximately one therm or one hundred thousand BTU's.

Distribution System
The system for carrying water to and from communities and industries, including treatment plants, pump stations, and pipe networks.

Effluent
Water or some other liquid, partially or completely treated, flowing from a reservoir, basin, treatment process or treatment plant.

Finished Water
Water that has passed through a water treatment plant; when all of the treatment processes are completed or "finished." This treated drinking water has met state and federal drinking water regulations and is ready to be delivered to consumers.

FOG
Fat, oil and grease can accumulate in wastewater pipes and block normal wastewater flows.

Hardness
A characteristic of water caused by various salts, calcium, magnesium and iron.

Influent
Water that flows into a reservoir, basin, treatment process or treatment plant.

Line Pack
The volumes of gas maintained in a pipeline at all times in order to maintain pressure and effect an uninterrupted transportation of natural gas through that pipeline.

Load
The amount of natural gas delivered or required at any specified point or points on a system.

Mains
Pipes used to carry natural gas, water, or sewage from one point to another. As contrasted with service pipes mains generally carry natural gas, water, or sewage in larger volumes for general collective use.

Mercaptan
An odorant added to natural gas to make it smell like rotten eggs that helps people notice natural gas leaks.

Non-Potable Water
Water that may contain objectionable pollution, contamination, minerals, or infective agents and that is considered unsafe and/or unpalatable for drinking.

Potable Water
Water that is safe to drink.

Raw Water
Water that has not been treated in anyway and is generally considered unsafe to drink.

Receiving Waters
All distinct bodies of water that receive runoff or wastewater discharges.

Reduced-Pressure Backflow Preventer
A device used to help prevent backflow into the distribution system.

Service Line
The pipe that carries natural gas or water from the main to the customer's meter.

Tennessee Department of Environment & Conservation (TDEC)
The State agency responsible for efforts to control air and water pollution.

Therm
A unit of heat equal to one hundred thousand BTU's.

Turbidity
The measure of the cloudiness of water, a good indicator of filter system operation.

Ultraviolet (UV) Disinfection
A disinfection process in which wastewater is exposed to UV light to kill or deactivate potential microbial pathogen.

United States Environmental Protection Agency (USEPA)
The U.S. agency responsible for efforts to control air and water pollution, radiation and pesticide hazards, ecological research, and solid waste disposal.