2020 census As of the
2020 census, Atwater had a population of 31,970 and a population density of . The census reported that 99.5% of residents lived in households, 0.2% lived in non-institutionalized group quarters, and 0.3% were institutionalized. There were 10,296 housing units at an average density of , of which 3.2% were vacant. Of the 9,970 occupied units, 55.9% were owner-occupied and 44.1% were occupied by renters.
2010 census At the
2010 census Atwater had a population of 28,168. The population density was . The racial makeup of Atwater was 18,410 (65.4%) White, 14,808 (52.6%) Hispanic or Latino of any race, 1,225 (4.3%) African American, 364 (1.3%) Native American, 1,416 (5.0%) Asian, 76 (0.3%) Pacific Islander, 5,300 (18.8%) from
other races, and 1,377 (4.9%) from two or more races. The census reported that 28,066 people (99.6% of the population) lived in households, 31 (0.1%) lived in non-institutionalized group quarters, and 71 (0.3%) were institutionalized. There were 8,838 households, 4,255 (48.1%) had children under the age of 18 living in them, 4,593 (52.0%) were
opposite-sex married couples living together, 1,558 (17.6%) had a female householder with no husband present, 672 (7.6%) had a male householder with no wife present. There were 615 (7.0%)
unmarried opposite-sex partnerships, and 60 (0.7%)
same-sex married couples or partnerships. 1,615 households (18.3%) were one person and 738 (8.4%) had someone living alone who was 65 or older. The average household size was 3.18. There were 6,823 families (77.2% of households); the average family size was 3.61. The age distribution was 9,016 people (32.0%) under the age of 18, 2,968 people (10.5%) aged 18 to 24, 7,492 people (26.6%) aged 25 to 44, 5,760 people (20.4%) aged 45 to 64, and 2,932 people (10.4%) who were 65 or older. The median age was 30.0 years. For every 100 females, there were 95.7 males. For every 100 females age 18 and over, there were 90.5 males. There were 9,771 housing units at an average density of 1,602.9 per square mile, of the occupied units 4,905 (55.5%) were owner-occupied and 3,933 (44.5%) were rented. The homeowner vacancy rate was 3.3%; the rental vacancy rate was 10.9%. 14,920 people (53.0% of the population) lived in owner-occupied housing units and 13,146 people (46.7%) lived in rental housing units.
2023 American Community Survey In 2023, the US Census Bureau estimated that 22.2% of the population were foreign-born. Of all people aged 5 or older, 52.5% spoke only English at home, 41.3% spoke
Spanish, 3.0% spoke other
Indo-European languages, and 3.2% spoke Asian or Pacific Islander languages. Of those aged 25 or older, 73.8% were high school graduates and 13.1% had a bachelor's degree. The median household income in 2023 was $63,945, and the
per capita income was $30,133. About 17.9% of families and 20.0% of the population were below the poverty line. ==Government==