Public Water System Type

The United States EPA (Environmental Protection Agency) and the Safe Drinking Water Act have outlined the definitions of three types of public water systems. As such, all the PWS data on can be divided up into these three water system types.

Keep in mind that the are water systems designed for drinking water (human consumption) in all of the 50 states as well as all tribal areas. Private wells are not covered by the SDWA or regulated by the EPA.

Also, drinking water standards vary based on the size of the water facility so the same rules and expectations cannot be applied across all water systems.

1. Community Water System (CWS)

This is a public water system that services the same population throughout the year.

2. Non-Transient Non-Community Water System

A NTNCWS is public water system that “regularly supplies water to at least 25 of the same people at least six months per year, but not year-round.” These generally are facilities that service buildings which are large enough to have their own water system, for example: schools, factories, and hospitals.

3. Transient Non-Community Water System

A TNCWS is a type of public water system that provides water where people do not live or habituate for extended periods of time. The examples the EPA uses in its documentation are camp grounds and gas stations.

Current EPA Data (February 2018)

Interesting water system facts from the CDC (sadly based on outdated 2007 data [PDF], but still interesting!)…