3
health. The variance shall be reviewed not less than every 5 years to determine if the system
remains eligible for the variance. During 2006, Illinois did not grant any variances.
A water system may also petition the state for an “exemption”. An exemption is permission not
to meet an MCL or a treatment technique under certain conditions for a period of time. An
exemption may be granted to give a water system additional time to make complicated and
expensive modifications and improvements to the water treatment process so that compliance
may be achieved in the shortest period of time. During 2006, Illinois did not grant any
exemptions.
Public Water System Overview
In Illinois, oversight of PWSs is divided between the Illinois Environmental Protection Agency
(Illinois EPA) and the Illinois Department of Public Health (Illinois DPH). Illinois EPA has been
designated as the lead agency for primary enforcement authority and oversees the community
public water system (CWS) program (these supplies that serve 15 or more year round service
connections or 25 or more year round residents). During 2006, there were 1,789 CWS. Illinois
DPH oversees the non-community water systems. Non-community systems include the non-transient,
non-community public water systems (NTNC) that serve 25 or more of the same
non-residents at least 180 days out of the year and include facilities such as day care centers,
schools and factories. Illinois DPH also oversees the transient non-community (TNC) public
water systems that serve 25 or more different nonresidents at least 60 days out of the year and
include facilities such as campgrounds and highway rest areas. During 2006, there were 396
NTNC and 3,822 TNC. The remainder of this report will detail the CWS supplies and then,
separately, address the non-community (NTNC/TNC) supplies.
Community Public Water Supplies
As previously mentioned, the
Illinois EPA oversees the CWS
program. A CWS is a PWS that
serves 25 or more people year
around and/or has 15 service
connections. Graph 1
depicts the breakdown of the
1,789 community water systems
within Illinois with regard to their
source of water. A total of
11,914,599 persons are served
by those systems; 41 percent of
that population is directly served
from surface water systems.
Thirty-four percent of the population is served by purchased surface water, 2 percent by
purchased ground water, and 23 percent by ground water systems. It is worth noting that
although only 23 percent of the population is served by ground water; ground water systems
comprise almost 58 percent (1,038 of the 1,789) of the total number of community water
systems. The type of source water (ground, surface, or purchase) for a CWS will determine
Graph 1. Population Served by Community Water Systems
by S ource Type
4,911,938
217,725
4,015,779
2,769,157
Ground Water Surface Water
Purchase Ground Water Purchase Surface Water
