ME Water Operator key terms

The rapid mixing of a chemical such as alum into raw water so that small particles lose their repelling charge and begin to clump together. It is the first step of conventional filtration treatment.

Gentle, slow stirring after coagulation that encourages tiny destabilized particles to collide and grow into larger, settlable clumps called floc. Speed and time are controlled so floc does not shear apart.

A quiet settling basin where water moves slowly enough for floc and heavier solids to sink to the bottom as sludge. Also called clarification, it removes most particles before filters do the polishing.

Passing water through beds of sand, anthracite, or other media to trap remaining particles, including protozoan cysts. Filters also must be monitored for head loss and breakthrough to stay effective.

The granular material, typically sand and anthracite coal, that makes up a filter bed. Grain size, uniformity, and depth determine how well particles are captured and how often backwashing is needed.

Reversing flow upward through a filter at high rate to lift and scrub the media, flushing trapped solids to waste. Operators watch for media loss and restart with a filter-to-waste or slow ramp-up.

Destroying or inactivating disease-causing organisms in treated water, usually with chlorine, chloramine, ozone, or ultraviolet light. It is the single most important barrier against waterborne illness.

The product of disinfectant concentration (C) in mg/L and contact time (T) in minutes used to judge how much pathogen inactivation is achieved. Required CT varies with disinfectant, pH, temperature, and target organism.

The period water is exposed to a disinfectant before the first customer draws it. Tanks and baffling are designed to provide enough time to meet the required CT value.

The amount of chlorine still present in water after treatment, measured as free or total chlorine. A detectable residual in the distribution system shows the water stays protected against contamination.

Chemicals such as trihalomethanes and haloacetic acids that form when chlorine reacts with natural organic matter. Operators balance enough disinfection against keeping these compounds below regulatory limits.

The cloudiness of water caused by suspended particles, measured in nephelometric turbidity units. It is a key indicator of filtration performance and can shield microbes from disinfection.

A bench-scale test using several beakers stirred at controlled speeds to find the best coagulant dose and pH for the plant's current raw water. Results guide full-scale chemical feed adjustments.

A measure of carbon in natural organic material dissolved or suspended in water. High levels raise disinfection byproduct risk and can be reduced by coagulation or granular activated carbon.

The network of pipes, storage tanks, pumps, and valves that carries finished water from the treatment plant to customers. Its condition strongly affects water quality at the tap.

A large buried pipe that forms the primary arteries of the distribution system. Mains are sized for fire flow and are flushed, repaired, and replaced to control breaks and water quality problems.

Any actual or potential link between the drinking water supply and a source of contamination, such as a submerged hose or an industrial process line. Preventing these links is central to distribution safety.

Water flowing opposite to its intended direction, driven by backpressure or backsiphonage, which can pull contaminants into the supply. It is stopped by properly selected and tested prevention assemblies.

Devices and practices, such as air gaps, reduced-pressure-zone assemblies, and vacuum breakers, that keep water from reversing into the potable supply. Assemblies must be tested on a set schedule.

A physical separation between a drinking water outlet and the highest possible level of a contaminant source. It is the most reliable and simplest form of backflow protection.

A portion of the distribution system bounded by valves or pumps that is maintained at a similar hydraulic head. Zones keep pressures within acceptable ranges and simplify leak detection and metering.

A valued connection on a water main used by fire crews and for flushing mains. Regular inspection, draining, and operation prevent sediment buildup and ensure flow during emergencies.

Opening one hydrant at a time while isolating a section of main so water flows in a single direction at high velocity. It scours sediment and biofilm from pipes more effectively than random flushing.

The rate and duration of water delivery a system must supply for firefighting at a given location. Mains, storage, and pumping are sized to meet this demand while maintaining customer pressure.

A pressure surge caused by a sudden change in flow, such as a quickly closed valve. It can crack pipes and damage fittings, so valves are operated slowly and surge protection is installed.

The untreated water drawn from a river, lake, reservoir, spring, or well before any treatment. Its quality and variability drive how much treatment the plant must provide.

Water that collects on or flows over the land, such as rivers, lakes, and reservoirs. It is exposed to runoff and weather, so it usually needs filtration and disinfection under federal rules.

Water held in underground aquifers and reached through wells or springs. It is often naturally filtered and more stable in quality, though it can still carry contamination and require disinfection.

Groundwater that is hydraulically connected to surface water and can receive its contamination. Systems with this classification generally must provide filtration and disinfection like surface water plants.

The land area that drains to a particular river, lake, or reservoir. Protecting the watershed from pollution reduces treatment costs and lowers risk to the drinking water supply.

Managing the land around a well to prevent contaminants from reaching its recharge area. It includes sealing wells, controlling chemical use, and regulating activities within a mapped protection zone.

Legally enforceable limits on contaminants that pose health risks, such as nitrate, lead, and coliform bacteria. Public water systems must meet them and report results to regulators and customers.

The highest concentration of a regulated contaminant allowed in water delivered to customers. It is set as close to the health goal as feasible given treatment technology and cost.

Non-enforceable guidelines for contaminants that affect taste, odor, color, or appearance rather than health, such as iron and manganese. States may adopt them as enforceable rules.

An annual notice that each community water system delivers to customers describing source water, detected contaminants, and compliance with standards. It must be timely, accurate, and understandable.

A public notice telling customers to boil tap water before drinking, cooking, or brushing teeth because of confirmed or suspected contamination. It is issued and lifted only under regulator-approved procedures.

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, permitting, ventilation, and a standby attendant.

A procedure that isolates and locks energy sources so equipment cannot start while someone works on it. Each worker applies a personal lock and tag, and only that worker removes them.

Clothing and gear such as gloves, eye protection, respirators, and chemical suits that reduce a worker's exposure to hazards. It is the last line of defense after engineering and administrative controls.

A written plan describing how a utility will detect, respond to, and recover from incidents such as main breaks, contamination, or power loss. It assigns roles, contacts, and communication steps.

A systematic review of a water system's facilities and processes to identify weaknesses to intentional attack or natural hazards. Results feed security upgrades and emergency planning.