WATER QUALITY TERMS TO KNOW

ASO Valve: Automatic Shutoff Valve

Clarity/turbidity: Clarity, or how clear the water is, is measured in Nephelometric Turbidity Units (NTU). Turbidity is very fine silts and clays suspended in water that can make it appear cloudy.

Coliform Bacteria: Microscopic organisms in water that are used as indicators of possible contamination.

CTA: Cellulose Triacetate (this has been superseded by the TFC)

DB series: double pre-filter, block carbon

D.C.F.: Duplex carbon filter

Detection Level or Detection Limit: The detection limit is the lowest level at which a compound can be measured. The detection limit differs for each constituent, laboratory and test method. Some of these levels are quite small. For example, one part per billion (ppb) is like a drop of water added to an entire swimming pool.

DLR (Detection Limit for Reporting Purposes): In order to compare results from different laboratories, the State Department of Health Services established DLRs. This provides a common basis for reporting purposes. For example, if a laboratory reports that lead is not detectable, it is understood that the amount of lead in the water is less than 5 ug/l (the DLR for lead). In some cases, laboratories including LADWP's, can actually measure at lower levels.

g.a.c. filters: granulated activated carbon filters

GPH: gallons per hour

GPM: gallons per minute

ID: inside diameter

L: liter

LSI Units: The Langelier Saturation Index (LSI) is a measurement of the corrosive nature of water. Corrosive water reduces the life of a pipe by slowly eroding the pipe material.

: micron

g: micrograms

g/l: micrograms per liter

m3: cubic meter

MCL (Maximum Contaminant Level): The MCL is the highest allowable level set by the federal and state health agencies for contaminants that may occur in water.

mg/l: Milligrams per liter or parts per million.

MTBE: Methyl-Tert-Butyl Ether

ng/l: Nanograms per Liter or parts per trillion.

mhos/cm2: Micromhos per square centimeter is a measure of the electrical conductance of water which depends on its mineral content.

NA: Not analyzed. Samples were not analyzed because they were not required or because they are scheduled to be sampled in the near future.

ND: Not detected at DLR. Samples were analyzed and the constituent was not found at the detection limit for reporting purposes.

NS: No standard exists.

NSF: National Sanitation Foundation

OD: outside diameter

OEM: original equipment manufacturer

POU: Point-of-Use

PPB: parts per billion

PPM: parts per million

Primary Standards: Health-related standards established by federal and state agencies.

PSI: pounds per square inch of pressure

PSIG: pounds per square inch of pressure

Secondary Standards: Standards for constituents which affect taste, odor and appearance. They are not considered a health concern.

SP Membrane: specific performance membrane

TDS (Total Dissolved Solids): An overall indicator of the amount of minerals in water.

TFC membrane: Thin Film Composite membrane

TLC: Thin layer composite

TON (Threshold Odor Number): A measure of the intensity of an odor in water.

TT (Treatment Technique): Some regulations require a treatment technique in lieu of setting an MCL. Currently, LADWP is required to install corrosion control under the Lead and Copper Rule regardless of the lead and copper levels in the water.

THMs (Trihalomethanes): THMs are by-products of chlorine disinfection. Disinfectants are used to keep water free of bacteria and water-borne diseases. When chlorine mixes with certain naturally occurring organic substances in water, trihalomethanes are formed. Animal studies have shown that some trihalomethanes, in very high doses over an extended period of time, are suspected of causing cancer. The MCL for trihalomethanes is based on a continuous averaging of four quarters of sampling.

VOC: volatile organic compounds