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