| Index | Water Mill | New York | National |
| Average Test Scores | n/a | 56% | 48% |
| Student/Teacher ratio | n/a | n/a | 16:1 |
| Total public schools | n/a | 4,060 | 79,221 |
| Total private schools | n/a | 1,092 | 24,874 |
| Total post-secondary schools | n/a | 483 | 7,963 |

| Index | Water Mill | New York | National |
| Completed 8th grade | 96.9% | 83.5% | 84.3% |
| Completed high school | 96.4% | 82.1% | 83.0% |
| Completed some college | 78.7% | 59.5% | 59.4% |
| Completed associate degree | 65.9% | 43.4% | 38.5% |
| Completed bachelors | 59.5% | 34.7% | 30.3% |
| Completed masters | 31.5% | 15.1% | 11.5% |
| Completed professional degree | 12.4% | 4.2% | 3.3% |
| Completed doctorate | 2.1% | 1.5% | 1.3% |
There are a total of n/a public schools, n/a private schools and n/a post-secondary schools in Water Mill. Using the proficiency score averages, the average test scores for Water Mill, NY schools is n/a. The average student to teacher ratio is n/a. In Water Mill, NY, an average of 96.9% of students have completed 8th grade and an average of 96.4% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| Quogue, NY | 623 | 80% | 66.7% |
| Amagansett, NY | 530 | 80% | 66.7% |
| Mattituck, NY | 5,017 | 77% | 60.4% |
| Sag Harbor, NY | 2,034 | 65% | 34.4% |
| East Hampton, NY | 948 | 63% | 31.0% |
| Water Mill, NY | 1,911 | n/a |
| City | Population | Avg. Test Scores | National Avg. |
| Coupeville, WA | 1,911 | 63% | 30.2% |
| Bridgton, ME | 1,911 | 45% | 7.3% |
| Westhampton Beach, NY | 1,911 | 73% | 51.7% |
| Seeley, CA | 1,911 | 28% | 41.7% |
| Deatsville, AL | 1,911 | 56% | 17.5% |
| Water Mill, NY | 1,911 | n/a |