Drinking Water Glossary

is a chemical species, which donates protons or hydrogen ions (H+) and/or accepts electrons.

is the concentration of a contaminant, which, if exceeded, triggers treatment or other requirements that a water system must follow. The Action level for lead is 0.015 mg/L. The Action Level for Copper is 1.3 mg/L.

means the potential for a contaminant or disinfectant residual to cause acute health effects, i.e., death, damage or illness, as a result of a single period of exposure of a duration measured in seconds, minutes, hours, or days. An example of contaminant, which can cause an acute health risk, is nitrate.

is a physical break between the supply line and a receiving vessel.

is a water's capacity to resist changes in pH, i.e. it's buffering capacity. For surface water treatment plants, often alkalinity and TOC monitoring of raw and finished water is required.

is a chemical species which donates electrons or hydroxide ions (OH) or that accepts protons.

is the person who has overall responsibility for the day-to-day, hands-on, operation of a water treatment facility or the person who has overall responsibility for the day-to-day, hands-on, operation of a distribution system.

is a public water system serving at least 15 service connections used by yearlong residents or regularly serves at least 25 yearlong residents.

is the nine-year calendar year cycle during which public water systems shall monitor. Each compliance cycle consists of three three-year compliance periods.

is a public water system receiving some or all of its finished water from one or more wholesale systems.

is required for each community and non-transient-non-community (NTNC) water system. The CCR must include information on source water and water quality and must be sent to customers annually by July 1.

is an unprotected actual or potential connection between a potable water system used to supply water for drinking purposes and any source or system containing unapproved water source or other substance.

is a reservoir, directly connected with the distribution system of the domestic water supply project, used primarily to care for fluctuations in demand which occur over short periods of from several hours to several days, or as local storage in case of emergency such as a break in a main supply line or failure of pumping plant.

is an assembly of at least two independently acting check valves including tightly closing shut-off valves on each side of the check valve assembly and test cocks available for testing the watertightness of each check valve.

is the process which enhances agglomeration or collection of smaller floc particles into larger, more easily settleable or filterable particles through gentle stirring by hydraulic or mechanical means.

of surface water means any water beneath the surface of the ground with significant occurrence of insects or other macroorganisms, algae or large diameter pathogens such as Giardia lamblia or Cryptosporidium, or significant and relatively rapid shifts in water characteristics such as turbidity, temperature, conductivity or pH which closely correlate to climatological or surface water conditions.

is the average of sample analytical results for samples taken at a particular monitoring location during the previous four calendar quarters. This term is used for compliance of Disinfection By Products.

is the highest level of a contaminant allowed in drinking water. Primary MCLs are set as close to the PHGs (or MCLGs) as is economically and technologically feasible.

is the amount of water utilized by consumers during the highest day of use (midnight to midnight), excluding fire flow. At all times, a water system must have enough capacity to meet maximum day demand.

means a level of a disinfectant added for water treatment, which may not be exceeded at the consumer's tap. The most common MRDL is 4 mg/L for chloramines or chlorine.

is a series of water treatment processes that provide for both removal and inactivation of waterborne pathogens.

is the value, which is used to determine compliance for the Lead and Copper Rule. The way in which a water system determines the 90th is to place all the sample results in ascending order from the sample with the lowest concentration to the sample with the highest concentration and calculate 90th percentile from there.

Non-transient-non-community (NTNC) water system is a public water system, which is not a community water system and regularly serves at least the same 25 persons over 6 months per year.

is the level of a contaminant in drinking water below, which there is no known or expected risk to health. PHGs are set by the Environmental Protection Agency.

is a backflow preventer incorporating not less than two check valves, an automatically operated differential relief valve located between the two check valves, a tightly closing shut-off valve on each side of the check valve assembly, and equipped with necessary test cocks for testing.

was effective April 1, 2016. The revisions include the new Coliform Treatment Technique requirement replacing the Total Coliform MCL, and a new E.coli MCL regulatory limit.

located between the two check valves, a tightly closing shut-off valve on each side of the check valve assembly, and equipped with necessary test cocks for testing.

is an on-site review of a public water system for the purpose of evaluating the adequacy of the water source, facilities, equipment, operation and maintenance for producing and distributing safe drinking water. There are eight elements to a Sanitary Survey:

(1) Source,

(2) Treatment,

(3) Distribution system,

(4) Finished water storage,

(5) Pumps, pump facilities, and controls,

(6) Monitoring, reporting, and data verification,

(7) System management and operation, and

(8) Operator compliance with State requirements.

is a process for removal of settleable solids before filtration by gravity or separation.

is a person in direct charge of the operation of a water treatment facility or distribution system for a specified period of the day.

is a process involving passage of raw water through a bed of sand at rates not to exceed 0.10 gpm/ ft2 resulting in substantial particulate removal by physical and biological mechanisms.

is a source, which is used only for emergency purposes of five consecutive days or less, and for less than a total of fifteen calendar days a year.

refers to all water open to the atmosphere and subject to surface runoff.

is a non-community water system not regularly serving at least 25 of the same persons over six months per year.

is the area contained in a drainage basin, which is tributary to a water supply diversion point.