CA Branch 1 key terms

A report identifying the origin of a system's water and the potential contaminant threats near it, used to prioritize monitoring and protection efforts. Required under the Safe Drinking Water Act.

Managing land use and activities in the drainage area supplying a reservoir or intake to keep contaminants out of raw water, reducing treatment cost and risk.

Untreated water as it enters the plant from a well, river, lake, or aqueduct, before any coagulation, filtration, or disinfection step is applied.

The cloudiness of water caused by suspended particles that scatter light, measured in nephelometric turbidity units and used as a key indicator of filtration performance.

The amount of chemical such as alum, ferric chloride, or polyaluminum chloride added per volume of water to destabilize particles and begin floc formation.

A bench-scale simulation in which several beakers of raw water receive different coagulant doses and mixing speeds, allowing operators to select the best chemical dose and pH.

A measure of the electrical charge at the slipping plane around a particle; near zero indicates particles are destabilized and likely to stick together during flocculation.

Gentle, slow stirring after rapid mix that encourages destabilized particles to collide and grow into larger, settleable floc without breaking the flocs apart.

The downward speed a particle reaches when drag balances its submerged weight; particles with higher settling velocity are removed more readily in a clarifier.

The flow through a sedimentation basin divided by its surface area, expressed as flow per area per day; it sets the minimum settling velocity a basin can capture.

The flow through a filter divided by its surface area, usually expressed in gallons per minute per square foot; higher rates reduce contact time and can worsen effluent quality.

The period a filter operates between backwashes, during which head loss rises and effluent turbidity may creep upward as captured particles accumulate in the media.

Reversing flow upward through a filter at a rate that expands the media bed and flushes captured solids to waste, restoring the filter for another run.

Diverting the first filtered water after backwash to drain until turbidity falls below a set limit, preventing a spike of particles from entering finished water.

The product of disinfectant residual concentration and contact time, used to demonstrate that a required level of pathogen inactivation has been achieved.

A way of expressing pathogen reduction as powers of ten; two-log inactivation means 99 percent of the target organisms are destroyed, three-log means 99.9 percent.

Compounds such as trihalomethanes and haloacetic acids formed when chlorine reacts with natural organic matter; regulated because long-term exposure raises health concerns.

The concentration of carbon bound in organic compounds in water; it is the precursor material for disinfection byproducts and is often reduced by coagulation or carbon adsorption.

The concentration of disinfectant remaining in treated water, maintained to protect against microbial regrowth and contamination as water travels through the distribution system.

Adding a small dose of chlorine at points in the distribution system to restore residual that has decayed, extending protection to distant or slow-moving areas.

A calculated number comparing measured pH to the pH at which water is exactly calcium carbonate saturated; near zero suggests balanced water, negative is corrosive, positive is scale-forming.

Adjusting pH, alkalinity, or adding inhibitors such as orthophosphate to keep pipe material from dissolving into finished water and to protect metal plumbing.

A regulation requiring systems to sample tap water at high-risk homes and, if action levels are exceeded, to optimize corrosion control and conduct public education.

A graph of the head a pump can produce at various flow rates; the point where it crosses the system curve is the actual operating condition.

A graph showing the head required to move water through a given piping network at each flow rate, combining static lift and friction losses.

Vapor bubbles forming and collapsing inside a pump when suction pressure drops too low, causing noise, vibration, and damage to the impeller over time.

The absolute pressure margin above a liquid's vapor pressure at the pump suction; too little available margin allows cavitation to begin.

Comparing an instrument's reading against a known standard and adjusting it so the displayed value matches the true value within an acceptable tolerance.

An instrument that shines light through a sample and measures scattered light to report turbidity; it must be calibrated and its sample cell kept clean and free of scratches.

A single volume collected at one place and time, giving an instant snapshot rather than an average; useful for process checks and for tests that cannot be composited.

Several portions collected over time or across locations and combined, producing an average result that may hide short-term peaks in quality.

A documented record of who collected, handled, and transported a sample and when, used to prove the sample's integrity if results are challenged.

The theoretical average time water spends in a basin or pipe, calculated as volume divided by flow rate; used in disinfection and settling calculations.

Entering a vault, tank, or pit with limited access and poor ventilation, requiring atmospheric testing, a permit, an attendant, and rescue provisions before anyone goes in.

A procedure for isolating and locking energy sources before servicing equipment so that pumps or mixers cannot start unexpectedly and injure workers.

Evacuating upwind, calling for trained responders, and using respiratory protection and leak kits; never entering a gas cloud without proper equipment and backup.

An annual notice telling customers where their water comes from, what contaminants were detected, and any health effects, delivered by a required deadline.

Any actual or potential link between the drinking water supply and a source of contamination, prevented by air gaps, backflow preventers, and routine inspections.

Devices and practices such as air gaps, reduced-pressure assemblies, and vacuum breakers that stop water from flowing backward into the potable system.

Tanks and reservoirs holding treated water for demand peaks and fire flow; they must be covered, inspected, and operated to keep water fresh and residual intact.