Water and sewer services are provided by separate public agencies and not by the City itself. 
Most Lake Forest residents are served by the Irvine Ranch Water District (formerly the Los Alisos
Water District).  However, the water district that serves your home will depend on the location
of your residence.

Irvine Ranch Water District
15600 Sand Canyon Ave.
Irvine, CA 92618-3102
(949) 453-5300
http://www.irwd.com/

El Toro Water District
24251 Los Alisos Blvd.
Lake Forest, California 92630
(949) 837-7050
http://www.etwd.com/

Trabuco Canyon Water District
32003 Dove Canyon Drive
Trabuco Canyon, CA 92679
(949) 858-0277
http://www.tcwd.ca.gov/