Glenbrook is an unincorporated community

Unincorporated area

In law, an unincorporated area is a region of land that is not a part of any municipality.To "incorporate" in this context means to form a municipal corporation, a city, town, or village with its own government. An unincorporated community is usually not subject to or taxed by a municipal government...

 in Lake County

Lake County, California

Lake County is a county located in the north central portion of the U.S. state of California, north of the San Francisco Bay Area. It takes its name from Clear Lake, the dominant geographic feature in the county and the largest natural lake wholly within California...

, California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

. It is located 10 miles (16 km) south-southeast of Kelseyville

Kelseyville, California

Kelseyville is a census-designated place in Lake County, California, United States. Kelseyville is located southeast of Lakeport, at an elevation of 1384 feet...

, at an elevation of 2293 feet (699 m).

A post office operated at Glenbrook from 1877 to 1911.

Astorg Spring (also called Tunnel Spring) is located 1 miles (1.6 km) southeast of Glenbrook. Water from this disused mining shaft was sent by tanker to San Francisco

San Francisco, California

San Francisco , officially the City and County of San Francisco, is the financial, cultural, and transportation center of the San Francisco Bay Area, a region of 7.15 million people which includes San Jose and Oakland...

for carbonation and distribution to the public.