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Table 1 Characteristics of community water systems (CWSs) and median demographics of the counties they serve

From: Environmental justice and drinking water quality: are there socioeconomic disparities in nitrate levels in U.S. drinking water?

System characteristics Study population Nitrate characteristics Median county demographic characteristics
Number of CWSs Population served CWSs ≥5 mg/L NO3-N (%) 95th percentile [NO3-N] (mg/L) Percent Black, non-Hispanic (Q1, Q3) Percent Hispanic (Q1, Q3) Percent below poverty line (Q1, Q3) Percent home ownership (Q1, Q3)
Overall 39,466 233,153,669 4.2 4.60 3.0 (0.8, 11.2) 6.0 (2.6, 13.1) 15.0 (11.5, 18.6) 70.9 (65.1, 75.9)
System Size
 V. Small 23,198 3,624,068 4.8 4.89 2.6 (0.8, 9.6) 6.4 (2.8, 13.2) 14.7 (11.3, 18.3) 70.3 (64.9, 75.6)
 Small 9867 13,934,810 3.7 4.30 3.2 (0.8, 12.8) 4.8 (2.1, 11.8) 15.6 (11.9, 19.5) 72.5 (67.2, 76.8)
 Medium 3437 20,032,495 2.7 3.78 4.2 (1.1, 14.3) 4.9 (2.3, 12.6) 16.1 (12.2, 19.6) 71.4 (65.7, 76.0)
 Large 2614 75,884,314 2.9 3.92 5.0 (1.8, 11.6) 6.8 (3.1, 15.7) 15.3 (11.6, 18.8) 69.4 (63.4, 74.3)
 V. Large 350 119,677,982 3.1 4.03 9.6 (4.9, 17.6) 13.4 (6.4, 27.7) 15.5 (12.5, 18.4) 63.4 (57.7, 68.1)
Region
 Midwest 8869 42,146,514 5.5 5.20 1.2 (0.5, 4.0) 2.9 (1.7, 5.3) 13.4 (10.8, 16.7) 74.5 (69.8, 78.0)
 Northeast 6572 31,734,958 3.5 4.34 2.6 (1.0, 5.1) 3.8 (1.8, 9.3) 11.6 (9.1, 14.2) 71.7 (68.3, 76.2)
 South 14,452 94,026,660 2.4 3.34 14.6 (6.0, 25.7) 6.1 (3.2, 14.1) 18.0 (13.7, 21.4) 71.8 (64.9, 75.9)
 West 9573 65,245,537 6.1 5.42 1.0 (0.5, 2.6) 12.7 (7.8, 30.6) 16.0 (12.3, 19.3) 65.7 (60.1, 70.2)
Source Water
 Groundwater 35,215 80,860,916 4.5 4.78 3.2 (0.9, 12.1) 6.1 (2.6, 13.0) 14.9 (11.4, 18.5) 71.0 (65.1, 76.0)
 Surface water 4251 152,292,753 1.2 2.64 2.3 (0.8, 6.7) 5.5 (2.4, 13.1) 15.8 (12.3, 19.3) 70.6 (65.2, 75.1)