Largest public system
- Lancaster County Water & Sewer District: Disinfectant
- Chloramine
- Lancaster County Water and Sewer District, 2025
- Lancaster County Water & Sewer District: TTHM (disinfection byproducts)
- 53.1 ppb
- Highest running annual average (2025); federal limit 80 ppb.
- Lancaster County Water and Sewer District, 2025
- Lancaster County Water & Sewer District: HAA5 (disinfection byproducts)
- 10 ppb
- Highest running annual average (2025); federal limit 60 ppb.
- Lancaster County Water and Sewer District, 2025
- Lancaster County Water & Sewer District: Lead (at sampled homes' taps)
- 5 ppb
- 90th percentile of homes sampled (2025). The federal action level is 15 ppb.
- Lancaster County Water and Sewer District, 2025