MA Water Operator key terms

A state review of a public water system's intake area that identifies potential contamination sources and rates how susceptible the supply is to them. Results inform monitoring waivers and protection planning.

The land surface and subsurface zone around a well through which contaminants could reasonably travel to reach the well. Delineated by time-of-travel or fixed radius, it guides land-use controls.

The area of an aquifer that supplies water to a pumping well under current pumping conditions. It shifts with pumping rate, water level, and nearby wells, so it must be re-evaluated when conditions change.

The cone-shaped lowering of the water table or piezometric surface around a pumping well. Its shape and slope indicate aquifer properties and how far pumping influence extends.

The cloudiness of water caused by suspended particles that scatter light. Measured in nephelometric turbidity units, it is a key treatment-performance and pathogen-barrier indicator, especially for filtered surface water.

Nephelometric turbidity unit, the standard measure of light scatter by suspended particles. Regulations set combined-filter-effluent and individual-filter limits in NTU, with stricter triggers for conventional filtration.

The chemical process of neutralizing particle surface charge so small suspended solids and colloids can stick together. It is the first step of conventional clarification and depends on dose, pH, and mixing energy.

Gentle, prolonged mixing that encourages destabilized particles to collide and grow into larger, settleable floc after coagulant is added. Excessive shear breaks floc apart and carries over to filters.

A bench-scale simulation of coagulation, flocculation, and settling using identical beakers at different chemical doses or pH values. It predicts full-scale chemical feed settings and optimal treatment conditions.

The pathogen reduction a treatment process is credited with, expressed as base-10 logarithm units. Credits come from approved tables based on turbidity, disinfectant residual, and process performance rather than from measurement alone.

The product of disinfectant residual concentration in milligrams per liter and contact time in minutes at a given temperature and pH. It quantifies disinfection effectiveness against Giardia and viruses.

The amount of chlorine consumed by reducing agents, organics, and other constituents in water before a measurable free residual persists. High demand requires higher dose to maintain a target residual.

The concentration of hypochlorous acid and hypochlorite ion remaining after chlorine demand is satisfied. It is the form that provides ongoing disinfection protection in the distribution system.

The sum of free chlorine and combined chlorine (chloramines) remaining in water. Comparing it with free residual reveals how much chlorine has reacted with ammonia or other nitrogen compounds.

The point on a chlorine dose curve where combined chlorine has been oxidized and further added chlorine appears as free residual. Operating beyond it avoids taste and odor problems from chloramines.

A combined chlorine compound formed when chlorine reacts with ammonia, used as a secondary disinfectant that persists longer in large distribution systems. It is weaker than free chlorine and requires careful ammonia control.

A chemical formed when disinfectants react with natural organic matter or bromide in water, such as trihalomethanes and haloacetic acids. Regulated by running annual averages at distribution sampling locations.

Total trihalomethanes, the sum of chloroform, bromodichloromethane, dibromochloromethane, and bromoform. Compliance is based on a locational running annual average of quarterly samples.

A measure of organic material in source water that can form disinfection byproducts and consume disinfectant. Enhanced treatment steps remove it before disinfection where required.

Regulation requiring corrosion control treatment and tap sampling at high-risk homes to limit lead and copper at the consumer's tap. Action levels trigger treatment changes, public education, and sometimes source replacement.

Adjusting water chemistry, such as pH, alkalinity, or inhibitor dose, to keep pipe material from dissolving into drinking water. It protects public health and extends distribution infrastructure life.

A calculated number comparing actual pH with the pH at which water is calcium carbonate saturated. A negative value suggests scale-dissolving water; a positive value suggests scale-forming tendency.

The water's capacity to neutralize acid, mainly from bicarbonate, carbonate, and hydroxide. It buffers pH changes, affects coagulation and corrosion control, and is reported as calcium carbonate equivalent.

The concentration of dissolved calcium and magnesium, usually reported as calcium carbonate equivalent in milligrams per liter. It affects scaling, soap consumption, and treatment chemical doses.

A group of bacteria used as indicators of treatment effectiveness and distribution contamination. Their presence in a routine sample triggers repeat and check sampling under the total coliform rule.

A coliform bacterium that indicates likely fecal contamination when found in a distribution sample. Its detection requires public notification and immediate investigation of the system.

A general test of bacteria that grow on nutrient-rich media, used to gauge overall distribution water quality and treatment changes. High counts can indicate biofilm growth or loss of disinfectant residual.

A community of microorganisms attached to pipe surfaces and embedded in a slime layer. It protects bacteria from disinfectants, contributes to corrosion, and can seed coliform detections.

The regulation that sets monitoring frequency and sample numbers for coliform bacteria based on population served. Positive results require repeat sampling and corrective action, with maximum contaminant level violations tied to repeat positives.

An on-site inspection by the state that evaluates a public water system's sources, facilities, operations, and records for contamination risks and compliance problems. Findings must be corrected on a schedule.

An annual water quality report delivered to customers that lists detected contaminants, their levels, and regulatory limits. It must be distributed by the required deadline and made publicly available.

Any actual or potential link between a potable water supply and a source of contamination or nonpotable fluid. It is controlled through air gaps, backflow preventers, and a cross-connection control program.

A testable device such as a reduced-pressure-zone or double-check assembly installed to stop reverse flow of nonpotable water into a distribution system. It must be tested on a set schedule by a certified tester.

A physical separation between a water supply outlet and the flood level of a receiving vessel. It is the most reliable backflow protection because it relies on no mechanical parts.

A pressure surge caused by rapid changes in flow velocity, such as sudden valve closure, that can damage pipes and fittings. Control measures include slow-closing valves and surge tanks.

A line showing the piezometric head along a pipeline, equal to elevation head plus pressure head. Its slope indicates head loss, and where it falls below the pipe, negative pressure can draw in contamination.

The energy lost to friction and fittings as water moves through pipe, expressed in feet or meters of head. It determines required pump pressure and is calculated with flow, pipe size, and roughness.

A graph of the head a pump can develop at various flow rates. It is plotted against the system curve to find the operating point where supply matches demand.

A graph of the head required to move water through a given system at various flow rates, combining static lift and friction losses. The intersection with a pump curve defines the operating point.

The absolute pressure head at a pump suction above the liquid's vapor pressure, needed to prevent cavitation. Available NPSH must exceed required NPSH specified by the pump manufacturer.

The formation and collapse of vapor bubbles in a pump when suction pressure falls too low, causing noise, vibration, and impeller damage. It reduces capacity and shortens equipment life.

The water level in a well when the pump is off and the aquifer is at rest. It is the baseline for measuring drawdown and setting pump depth.

The difference between static and pumping water levels in a well. It reflects pumping rate, aquifer transmissivity, and well efficiency, and is monitored to detect well fouling.

A space large enough to enter, with limited entry or exit, not designed for continuous occupancy, such as a vault or wet well. Entry requires testing, permits, attendants, and rescue provisions.

The procedure of isolating and locking energy sources before maintenance so equipment cannot start unexpectedly. Each worker applies a personal lock and verifies zero energy before work begins.

The requirement to label containers, maintain safety data sheets, and train employees about chemical hazards in the workplace. It covers treatment chemicals, fuels, and disinfectants stored on site.

A public health advisory telling customers to boil water before drinking when the system may be contaminated or pressure is lost. It must be issued within mandated timeframes and lifted only after testing confirms safety.

The theoretical time water spends in a tank or basin, calculated as volume divided by flow rate. It governs disinfection contact, settling, and chemical reaction completeness.

The flow applied per unit surface area of a treatment unit, such as a filter or clarifier, usually in gallons per minute per square foot. It affects settling efficiency and filter run length.

The flow through a settling basin divided by its surface area, expressed in gallons per day per square foot. Particles with settling velocity greater than this rate are removed.

Well yield per unit of drawdown, typically gallons per minute per foot. Declining specific capacity signals clogging, screen fouling, or declining aquifer performance.

An instrument that reads the pressure head at a point in a piping system, usually in psi. Readings converted to feet of head reveal elevation differences and friction losses.

A device that continuously measures the volume or rate of water passing a point, used for billing, process control, and regulatory reporting. Accuracy must be verified by periodic calibration.

A field test in which a tracer is added at a basin inlet and monitored at the outlet to determine actual contact time. Results replace theoretical detention time in disinfection calculations.