AR Water Operator key terms

Water taken from a source such as a river, lake, or well before any treatment is applied. Its quality determines what treatment processes a plant must use.

Water that has passed through all treatment processes and is ready to enter the distribution system or be delivered to customers.

Voluntary and regulatory actions that prevent contamination of lakes, rivers, springs, and aquifers used for drinking water, such as land-use controls and spill response planning.

The land surface around a public well where contaminants could travel to the well within a set time, often used to restrict activities that threaten groundwater.

An underground layer of sand, gravel, or rock that holds and transmits groundwater in usable quantities. Wells draw drinking water from aquifers.

The rapid mixing of a chemical such as alum into water to neutralize particle charges so small suspended solids can clump together and later be removed.

Gentle, slow stirring that encourages destabilized particles to collide and grow into larger, settleable clumps called floc after coagulant is added.

The visible clump of aggregated particles and coagulant chemicals that forms during flocculation and can be removed by settling or filtration.

A settling basin or clarifier process in which gravity removes floc and other suspended solids from water before it moves on to filtration.

Passing water through beds of sand, anthracite, or membranes to remove remaining particles, turbidity, and many microorganisms that survived settling.

Reversing or expanding flow through a filter to flush out trapped particles and restore the filter's ability to remove turbidity and organisms.

The period a filter operates between backwashes. Operators end a run when head loss or effluent turbidity reaches a set limit.

The drop in water pressure or level as water moves through a filter or pipe. Rising filter head loss signals clogging and the need to backwash.

Treating water with chlorine, ozone, ultraviolet light, or another agent to inactivate disease-causing organisms and provide a residual in the distribution system.

The amount of chlorine remaining in water after treatment and during distribution. It shows that disinfecting power is still present and protects against contamination.

The product of disinfectant concentration (C) and contact time (T) used to judge whether a given level of pathogen inactivation has been achieved.

Compounds such as trihalomethanes and haloacetic acids that form when disinfectants react with natural organic matter in water. They are regulated in finished water.

A measure of organic material in water. High levels can feed bacterial growth and form disinfection byproducts when chlorine is added.

Cloudiness caused by suspended particles that scatter light. It is measured in nephelometric turbidity units and is a key indicator of treatment performance and microbial risk.

A laboratory or online instrument that measures turbidity by detecting light scattered at an angle by particles suspended in a water sample.

A bench-scale procedure that stirs several beakers of raw water with different chemical doses to find the best coagulant dose and mixing conditions.

A group of bacteria used as indicators of contamination and treatment effectiveness. Their presence in finished water can signal a pathway for pathogens.

A general test that counts bacteria able to grow on nutrient media. It is used to monitor biological conditions and regrowth in distribution water.

A community of microorganisms attached to pipe walls or other surfaces. It can protect pathogens, cause odors, and contribute to corrosion and regrowth problems.

A biological process in which ammonia is converted to nitrite and then nitrate, often in chloraminated systems. It consumes disinfectant and can cause water quality complaints.

Disinfection using chloramines formed by combining chlorine with ammonia. It produces fewer regulated byproducts but requires careful ammonia control and monitoring for nitrification.

Any actual or potential link between the drinking water system and a source of contamination or nonpotable water that could allow backflow into the pipes.

A testable device such as a reduced-pressure zone assembly installed to stop contaminated water from reversing flow into a public water system.

A physical separation between a water supply outlet and the flood level of a receiving vessel. It is the most reliable form of backflow protection.

A pressure surge caused by sudden changes in flow velocity, such as rapid valve closure. It can damage pipes, joints, and meters.

The level of water in a well when the pump is off and the water has stabilized. It is used to track aquifer conditions and well performance.

The drop in water level in a well or storage tank caused by pumping or by demand. Excessive drawdown can indicate overpumping or a failing source.

The difference between water produced or purchased and water sold or otherwise accounted for. It includes leaks, meter error, and unauthorized use.

A systematic accounting of water supply, sales, and losses in a utility. It identifies real and apparent losses and guides leak-reduction efforts.

The use of listening devices, acoustic loggers, flow monitoring, or surveys to find hidden pipe leaks that waste treated water and can undermine pressure.

The highest concentration of a regulated contaminant allowed in drinking water under federal and state rules, based on health and technical feasibility.

A required treatment process or performance standard used instead of a maximum contaminant level when contaminant concentration is difficult or costly to measure.

A regulation that sets monitoring and repeat-sampling requirements for total coliforms and E. coli in distribution systems and defines when public notice is required.

The required process of informing customers when a public water system violates a drinking water standard or faces a serious risk, with tiers based on urgency.

An annual report that community water systems must provide to customers summarizing source water, detected contaminants, compliance, and health information.

A space with limited entry and exit that is not designed for continuous occupancy and may contain hazardous atmospheres, such as a vault or wet well.

A safety procedure that isolates energy sources and applies locks and tags so equipment cannot be started while workers service or repair it.

A toxic, flammable gas with a rotten-egg odor that can form in sewers and wet wells. It deadens the sense of smell at higher concentrations.

Precautions for handling chlorine gas, including ventilation, leak detection, respiratory protection, and knowledge of the gas's heavier-than-air behavior.