Third Lake is a village in Lake County, Illinois, United States. The population was 1,182 at the 2010 census.
Third Lake is located at 42°22′5″N 88°0′32″W (42.368117, -88.008903).
According to the 2010 census, Third Lake has a total area of 0.853 square miles (2.21 km2), of which 0.59 square miles (1.53 km2) (or 69.17%) is land and 0.263 square miles (0.68 km2) (or 30.83%) is water.
As of the census of 2000, there were 1,355 people, 428 households, and 369 families living in the village. The population density was 2,474.7 people per square mile (951.2/km2). There were 436 housing units at an average density of 796.3 per square mile (306.1/km2). The racial makeup of the village was 95.50% White, 0.52% African American, 1.92% Asian, 0.59% from other races, and 1.48% from two or more races. Hispanic or Latino of any race were 3.32% of the population.
There were 428 households, out of which 50.5% had children under the age of 18 living with them, 81.5% were married couples living together, 4.0% had a female householder with no husband present, and 13.6% were non-families. 9.3% of all households were made up of individuals, and 2.3% had someone living alone who was 65 years of age or older. The average household size was 3.14 and the average family size was 3.39.
In the village, the population was spread out, with 31.7% under the age of 18, 6.6% from 18 to 24, 30.1% from 25 to 44, 27.5% from 45 to 64, and 4.1% who were 65 years of age or older.