Oral Health Data Glossary

Frequently Asked Questions

What is the difference between Public Water System and Community Water System?
The vast majority of Public Water Systems in the US are Community Water Systems. The water systems tracked in WFRS are Community Water Systems as reported by the states. In a WFRS data set, the terms PWS and CWS can be used interchangeably.

Why is the state or county population reported by WFRS greater than the corresponding US Census population for the area?
Information in WFRS and MWF is reported by states to the CDC. PWS do not know the number of people they service, only the number of customers (i.e. water meters) that are connected to their system. Most PWS populations reported to WFRS are estimated based on the typical number of people served by each connection. As a result, these service populations may at times over-report an estimated population.

Why don’t indicators stratified by fluoridation status always add up exactly?
Most Fluoridated water systems in WFRS are Adjusted, Natural, or Consecutive. Other fluoridation status’ are possible, as reported in this Glossary under Fluoridation Status. For conciseness, these systems are not reported.

Glossary

A

Adjusted

A public water system with fluoride adjusted to the recommended level. An Adjusted system is always designated as Fluoridated. See also Fluoridation Status.

B
C

Community Water System
A public water system that serves the same people each day

Consecutive System
A water system that purchases water from another water system. EPA SDWIS reports all Consecutive relationships between PWS. CDC WFRS reports Consecutive relationships between systems that have a Fluoridated status as reported by the states.

Correlate
Laboratory precision comparison between split sample results

D

Defluoridated System

A water system that has high natural fluoride levels and actively reduces the fluoride level in the water delivered to consumers. Defluoridated systems are always Fluoridated.

E

F

Fluoridated

A water system that has fluoride at or above the recommended fluoride level which is 0.7 mg/L. The Fluoridation Status of the system can be Adjusted, Natural, Consecutive, Defluoridated, or even Variable.

Fluoridation

The adjustment of fluoride to a level beneficial for oral health

Fluoridation Status

The designation of a water system as Adjusted, Consecutive, Defluoridated, Multi-source, Natural, Non-adjusted, or Variable.

 

PWS Status	Description
Adjusted	Adds fluoride to raise the natural concentration up to the optimal level for the prevention of cavities Adds fluoride to raise the natural concentration up to the optimal level for the prevention of cavities May have its own water source. May purchase non-fluoridated water from another system, then add fluoride All Adjusted systems are designated as Fluoridated
Consecutive	May be fluoridated or non-fluoridated depending on the source Purchases water from another system Does not adjust the fluoride concentration
Defluoridated	The finished water fluoride concentration delivered to consumers is reduced either by a treatment process which removes fluoride from the water, OR Water with high fluoride is blended with waters with a low fluoride concentration Does not purchase water from another system Has a high natural fluoride concentration All Defluoridated systems are designated as Fluoridated
Multi-Source	Has multiple sources May have any of the following fluoridation statuses: Adjusted, Consecutive, Natural, Non-Adjusted May be fluoridated or non-fluoridated depending on the source
Natural	Has a natural fluoride concentration above the minimum control range for that owner May have an optimal control range that is different from the control range for an adjusted system
Non-Adjusted	Does not purchase water from another system Has a natural fluoride concentration below the minimum control range Does not adjust the fluoride concentration Is designated as non-fluoridated
Variable	Does not purchase water from another system Has multiple wells with different fluoride concentrations Note: With different wells with different fluoride concentrations, there may be zones of influence for each well in the distribution system having different fluoride concentrations depending on which neighborhood a residence may be located. Has fluoride concentration of the water delivered to consumers that varies widely throughout the year Does not fit into one of the other water system categories

Fluoride Product

The source of fluoride in water: natural geological sources, sodium fluoride, sodium fluorosilicate, or fluorosilicic acid

G

Ground Source

Water that comes from a well, spring or other subsurface extraction of water

H

I

In-Range

A sufficient number of samples reported to the CDC Water Fluoridation Reporting System were within the operating control range specified by the state

J

K

L

M

Multi-Source System

A water system that may have different sources of supply. See also Fluoridation Status.

N

Natural Systems

A water system that has natural fluoride equal to or greater than the recommended level. A Natural system is always designated as Fluoridated. See also Fluoridation Status.

Non-Adjusted

A public water system with insufficient fluoride for good oral health. A Non-Adjusted system is designated as Non-Fluoridated. See also Fluoridation Status.

Non-Optimal

A water system that adjusts fluoride but the PWS either did not stay within the stated operating control range or the state has not reported operational records to CDC Water Fluoridation Reporting System.

O

Optimal

A water system that adjusts fluoride to the recommended level and has documented operating within the states operational control range.

P

Points

Denotes a point-of-supply separate from other discrete sources.  A point can be a well, a river or lake intake, a connection to another adjacent water system or any discrete supply of water.  If a water system has two wells, it would have two points.

Public Water System

Defined by the U.S. Environmental Protection Agency as a water system that serves 25 or more persons in a day for at least 2 months of the year, or has 15 or more connections

PWS Split

See Split Sample

Q

R

S

Source

A source of water is a surface source such as a lake, river, reservoir, or groundwater sources such as a well or spring, or purchased water from an adjacent water system

Split Sample

Some states require periodic split sampling in which a water system will split a sample, test one part and report to the state, and the state tests the other part and compares the results to verify the accuracy of their testing method.

State Split

See Split Sample

Sufficient Samples

The water system has reported a sufficient number of samples to the CDC Water Fluoridation Reporting System.

Surface Source

A surface source of water is a river, lake, or reservoir

T

U

V

Variable Systems

Water systems that have multiple wells with different fluoride levels. May result in some neighborhoods having sufficient fluoride for oral health and other neighborhoods having insufficient fluoride for oral health. See also Fluoridation Status.

W

Water Source – Ground

Water extracted from groundwater sources through a well or spring

Water Source – Mixed

A public water system that obtains water from more than a single source  such as groundwater, surface water, or purchasing water from other water systems

Water Source – Surface

Water withdrawn from surface sources such as a river, lake, or reservoir

Water System ID

Unique seven-digit ID assigned through the Environmental Protection Agency Safe Drinking Water Information System

X

Y

Z